Stage drive method and stage unit, exposure apparatus, and device manufacturing method

ABSTRACT

When a transition from a first state where one stage is positioned at a first area directly below projection optical system to which liquid is supplied to a state where the other stage is positioned at the first area, both stages are simultaneously driven while a state where both stages are close together in the X-axis direction is maintained. Therefore, it becomes possible to make a transition from the first state to the second state in a state where liquid is supplied in the space between the projection optical system and the specific stage directly under the projection optical system. Accordingly, the time from the completion of exposure operation on one stage side until the exposure operation begins on the other stage side can be reduced, which allows processing with high throughput. Further, because the liquid can constantly exist on the image plane side of the projection optical system, generation of water marks on optical members of the projection optical system on the image plane side is prevented.

TECHNICAL FIELD

The present invention relates to stage drive methods and stage units,exposure apparatus, and device manufacturing methods, and moreparticularly to a stage drive method in which two stages movable in anarea including a first area within a two-dimensional plane where aliquid is locally supplied are driven and a stage unit suitable forimplementing the stage drive method, an exposure apparatus that suppliesliquid in a space between a projection optical system and a substrateand exposes the substrate via the projection optical system and theliquid, and a device manufacturing method that uses the exposureapparatus.

BACKGROUND ART

Conventionally, in a lithography process for manufacturing electronicdevices such as a semiconductor device (such as an integrated circuit),a liquid crystal display device or the like, a reduction projectionexposure apparatus by the step-and-repeat method that transfers an imageof a pattern of a mask or a reticle (hereinafter generally referred toas a ‘reticle’) onto each of a plurality of shot areas on aphotosensitive substrate such as a wafer coated with a resist(photosensitive agent), a glass plate, or the like (hereinaftergenerally referred to as a ‘substrate’ or a ‘wafer’) via a projectionoptical system, or a projection exposure apparatus by the step-and-scanmethod (the so-called scanning stepper (also referred to as a scanner))are mainly used.

Resolution R of the projection optical system that the projectionexposure apparatus has can be expressed as in equation (1) below byRayleigh's formula.R=k ₁ ·λ/NA  (1)

In this case, λ is the exposure wavelength, NA is the numerical apertureof the projection optical system, and k₁ is a process factor. Accordingto equation (1), resolution R becomes higher when the exposurewavelength used (the wavelength of the exposure light) becomes shorteror when the numerical aperture or the projection optical system (NA)becomes larger. Therefore, as the integrated circuit becomes finer, theexposure wavelength used in the projection exposure apparatus isbecoming shorter year by year, and nowadays, exposure apparatus thatuses the ArF excimer laser (wavelength 193 nm) whose wavelength isshorter than the KrF excimer laser (wavelength 248 nm) is also put topractical use. Further, the numerical aperture of the projection opticalsystem is gradually increasing.

When performing exposure, the depth of focus (DOF) is also important aswell as the resolution. Depth of focus δ can be expressed as in equation(2) below.δ=k ₂ ·λ/NA ²  (2)

In this case, k₂ is a process factor. From equations (1) and (2), it canbe seen that when exposure wavelength λ is shortened and numericalaperture NA is increased (a larger NA) in order to increase resolutionR, depth of focus δ becomes narrower. In the projection exposureapparatus, when exposure is performed, because the surface of the waferis made to conform to the image plane of the projection optical system,depth of focus δ should preferably be wide to some extent.

However, due to the shorter wavelength of the exposure light and thelarger numerical aperture of the projection optical system describedabove, the depth of focus is becoming narrower. Further, the exposurewavelength is presumed to be much shorter in the future; however, insuch a case, the depth of focus may become so small that focus marginshortage may occur during the exposure operation.

Therefore, as a method of substantially shortening the exposurewavelength while increasing (widening) the depth of focus when comparedwith the depth of focus in the air, the exposure apparatus that uses theimmersion method is recently gathering attention. As such an exposureapparatus using the immersion method, the apparatus that performsexposure in a state where the space between the lower surface of theprojection optical system and the wafer surface is locally filled withliquid such as water or an organic solvent is known (for example, referto Patent Document 1 below). According to the exposure apparatus ofPatent Document 1, the resolution can be improved by making use of thefact that the wavelength of the exposure light in the liquid becomes 1/nof the wavelength in the air (n is the refractive index of the liquidwhich is normally around 1.2 to 1.6), and the depth of focus can be alsosubstantially increased n times when compared with the case where thesame resolution is obtained by a projection optical system (supposingthat such a projection optical system can be made) that does not employthe immersion method. That is, the depth of focus can be substantiallyincreased n times than in the air.

However, in the exposure apparatus according to Patent Document 1, theliquid has to be recovered once at the point before the wafer stagemoves away from under the projection optical system during waferexchange, so as to change the state of the space between the lowersurface of the projection optical system and the wafer surface from awet state to a dry state. However, when the recovery and the supply ofthe liquid is performed each time the wafer is exchanged, it is certainthat the time required for the recovery and supply of the liquid willcause a decrease in throughput of the exposure apparatus.

Further, when the optical path space of the projection optical system onthe image plane side is changed from the wet state into the dry state inthe manner described above, in the case the dry state continues, waterstains (water marks) may be generated on the surface of the opticalmember constituting the projection optical system on the lowest end,which is also referred to as a front (lens) (such as a lens or a glassplate; hereinafter referred to as a ‘tip lens’). Further, in the case anoptical member (e.g. a prism or the like), which is a member configuringan autofocus mechanism, is arranged in the vicinity of the tip lens,water stains (water marks) may be generated on the surface of theoptical member configuring the autofocus mechanism. This water staingeneration may lead to a decrease in transmittance of the projectionoptical system or may be the cause of flare, and furthermore it may be acause of deterioration in other image-forming performances in theprojection optical system. Further, in the case water marks aregenerated on the prism or the like referred to above, there was the riskof the plane conforming accuracy decreasing when the surface of thewafer was made to conform to the image plane of the projection opticalsystem. Further, when many water marks are generated, the tip lens orthe optical member has to be replaced, however, the time required forthe replacement also becomes the cause of decreasing the operation rateof the exposure apparatus.

In the description, the stains that are formed on the tip lens or thelike also in the case of using liquid other than water will also bereferred to as water stains (water marks).

Patent Document 1: the Pamphlet of International Publication NumberWO99/49504

DISCLOSURE OF INVENTION

Means for Solving the Problems

The present invention has been made in consideration of the situationdescribed above, and according to a first aspect of the presentinvention, there is provided a stage drive method in which a first stageand a second stage are independently driven within an area in atwo-dimensional plane of a predetermined range including a first areawhere liquid is locally supplied and a second area located on one sideof the first area in a first axis direction, wherein on a transitionfrom a first state in which one stage of the first stage and the secondstage is positioned at the first area to a second state in which theother stage is positioned at the first area, the first stage and thesecond stage are simultaneously driven in a second axis directionintersecting the first axis direction while one of a state where thefirst stage and the second stage are close together in the second axisdirection and a state where the first stage and the second stage are incontact in the second axis direction is maintained.

In this case, ‘a state where the first stage and the second stage areclose together’ refers to a state where the first stage and the secondstage are close together so that the liquid does not leak from betweenthe first stage and the second stage or the leakage level of the liquidis low. However, the permissible value of the distance between the firststage and the second stage differs depending on the material of thestages and/or the type of the liquid. In the description, the expression‘a state where the first stage and the second stage are close together’is used in the sense described above.

According to this method, when independently driving the first stage andthe second stage within the area in a two-dimensional plane of apredetermined range including the first area where liquid is locallysupplied and the second area located on one side of the first area inthe first axis direction, in the case of a transition from the firststate where one stage of the first stage and the second stage ispositioned at the first area to the second state where the other stageis positioned at the first area, the first stage and the second stageare simultaneously driven in the second axis direction intersecting thefirst axis direction while a state where the first stage and the secondstage are close together in the second axis direction or a state wherethe first stage and the second stage are in contact in the second axisdirection is maintained. This allows the transition from the first stateto the second state, in a state where an immersion area is formed on atleast one stage of the first stage and the second stage, whilepreventing or suppressing the leakage of the liquid from the gap betweenthe first stage and the second stage (both stages). That is, it becomespossible to perform a transition from a state where the liquid is heldon one stage to a state where the liquid is held on both of the stagesand then to a state where the liquid is held on the other stage, withoutgoing through the process of fully recovering the liquid and supplyingthe liquid again. Accordingly, it becomes possible to perform thetransition from the first state to the second state within a shortperiod.

According to a second aspect of the present invention, there is provideda second stage drive method in which a first stage is driven within anarea in a two-dimensional plane of a predetermined range including afirst area where liquid is locally supplied and a second area located onone side of the first area in a first axis direction, and a second stageis driven within an area of a predetermined range including the firstarea and a third area located on the other side of the first area in thefirst axis direction, wherein on a transition from a first state inwhich one stage of the first stage and the second stage is positioned atthe first area to a second state in which the other stage is positionedat the first area, the first stage and the second stage aresimultaneously driven in the first axis direction while one of a statewhere the first stage and the second stage are close together in thefirst axis direction and a state where the first stage and the secondstage are in contact in the first axis direction is maintained.

According to this method, when driving the first stage within the areain the two-dimensional plane of a predetermined range including thefirst area where liquid is locally supplied and the second area locatedon one side of the first area in the first axis direction and alsodriving the second stage within the area of a predetermined rangeincluding the first area and the third area located on the other side ofthe first area in the first axis direction, in the case of a transitionfrom the first state where one stage of the first stage and the secondstage is positioned at the first area to the second state where theother stage is positioned at the first area, the first stage and thesecond stage are simultaneously driven in the first axis direction whileone of a state where the first stage and the second stage are closetogether in the first axis direction and a state where the first stageand the second stage are in contact in the first axis direction ismaintained. This allows the transition from the first state to thesecond state, in a state where an immersion area is formed on at leastone stage of the first stage and the second stage, while preventing orsuppressing the leakage of the liquid from the gap between the firststage and the second stage. That is, it becomes possible to perform atransition from a state where the liquid is held on one stage to a statewhere the liquid is held on both of the stages and then to a state wherethe liquid is held on the other stage, without going through the processof fully recovering the liquid and supplying the liquid again.Accordingly, it becomes possible to perform the transition from thefirst state to the second state within a short period.

According to a third aspect of the present invention, there is provideda first stage unit, the unit comprising: a first stage and a secondstage that are independently driven within an area in a two-dimensionalplane of a predetermined range, which includes a first area where liquidis locally supplied and a second area located on one side of the firstarea in a first axis direction; and a control unit that controls thefirst stage and second stage so as to simultaneously move the firststage and the second stage in a second axis direction intersecting thefirst axis direction while one of a state where the first stage and thesecond stage are close together in the second axis direction and a statewhere the first stage and the second stage are in contact in the secondaxis direction is maintained, on a transition from a first state inwhich one stage of the first stage and the second stage is positioned atthe first area to a second state in which the other stage is positionedat the first area.

According to this unit, when a transition is performed from the firststate where one stage of the first stage and the second stage ispositioned at the first area where the liquid is locally supplied withina two-dimensional plane to the second state where the other stage ispositioned at the first area, the control unit controls the first stageand second stage so as to simultaneously move the first stage and thesecond stage in the second axis direction intersecting the first axisdirection while one of a state where the first stage and the secondstage are close together in the second axis direction and a state wherethe first stage and the second stage are in contact in the second axisdirection is maintained. This allows the transition from the first stateto the second state, in a state where an immersion area is formed on atleast one stage of the first stage and the second stage, whilepreventing or suppressing the leakage of the liquid from the gap betweenthe first stage and the second stage (both stages). That is, it becomespossible to perform a transition from a state where the liquid is heldon one stage to a state where the liquid is held on both of the stagesand then to a state where the liquid is held on the other stage, withoutgoing through the process of fully recovering the liquid and supplyingthe liquid again. Accordingly, it becomes possible to perform thetransition from the first state to the second state within a shortperiod.

According to a fourth aspect of the present invention, there is provideda second stage unit, the unit comprising: a first stage that can bemoved within an area in a two-dimensional plane of a predetermined rangeincluding a first area and a second area located on one side of thefirst area in a first axis direction where liquid is locally supplied; asecond stage that can be moved within an area of a predetermined rangeincluding the first area and a third area located on the other side ofthe first area in the first axis direction; and a control unit thatcontrols the first stage and second stage so as to simultaneously movethe first stage and the second stage in the first axis direction whileone of a state where the first stage and the second stage are closetogether in the first axis direction and a state where the first stageand the second stage are in contact in the first axis direction ismaintained, on a transition from a first state in which one stage of thefirst stage and the second stage is positioned at the first area to asecond state in which the other stage is positioned at the first area.

According to this unit, when a transition is performed from the firststate where one stage of the first stage and the second stage ispositioned at the first area where the liquid is locally supplied withina two-dimensional plane to the second state where the other stage ispositioned at the first area, the control unit controls the first stageand second stage so as to simultaneously move the first stage and thesecond stage in the first axis direction while one of a state where thefirst stage and the second stage are close together in the first axisdirection and a state where the first stage and the second stage are incontact in the first axis direction is maintained. This allows thetransition from the first state to the second state, in a state where animmersion area is formed on at least one stage of the first stage andthe second stage, while preventing or suppressing the leakage of theliquid from the gap between the first stage and the second stage. Thatis, it becomes possible to perform a transition from a state where theliquid is held on one stage to a state where the liquid is held on bothof the stages and then to a state where the liquid is held on the otherstage, without going through the process of fully recovering the liquidand supplying the liquid again. Accordingly, it becomes possible toperform the transition from the first state to the second state within ashort period.

According to a fifth aspect of the present invention, there is provideda first exposure apparatus that supplies a liquid to a space between aprojection optical system and a substrate and exposes the substrate withan energy beam via the projection optical system and the liquid, theapparatus comprising: a first stage that can be moved within an area ofa predetermined range including a first area directly below theprojection optical system where the liquid is supplied and a second arealocated on one side of the projection optical system in a first axisdirection; a second stage that can be moved within an area of apredetermined range including the first area and a third area located onthe other side of the projection optical system in the first axisdirection; a stage drive system that drives the first stage and thesecond stage, as well as simultaneously drives the first stage and thesecond stage in the first axis direction while one of a state where thefirst stage and the second stage are close together in the first axisdirection and a state where the first stage and the second stage are incontact in the first axis direction is maintained, on a transition froma first state in which one stage of the first stage and the second stageis positioned at the first area to a second state in which the otherstage is positioned at the first area; a first mark detection systemarranged above the second area that detects a mark located on the firststage; and a second mark detection system arranged above the third areathat detects a mark located on the second stage.

According to this apparatus, when a transition is performed from thefirst state where one stage is positioned at the first area directlybelow the projection optical system where the liquid is supplied to asecond state where the other stage is positioned at the first area, thestage drive system simultaneously drives the first stage and the secondstage in the first axis direction while one of a state where the firststage and the second stage are close together in the first axisdirection and a state where the first stage and the second stage are incontact in the first axis direction is maintained. This allows thetransition from the first state to the second state, in a state wherethe liquid is held in the space between the projection optical systemand at least one stage directly below the projection optical system,while preventing or suppressing the leakage of the liquid from the gapbetween the first stage and the second stage. That is, during the periodafter the exposure operation of the substrate via the projection opticalsystem and the liquid using the one stage has been performed until theexposure operation of the substrate via the projection optical systemand the liquid using the other stage begins, it becomes possible toperform the transition from a state where the liquid is held or retainedin the space between the one stage and the projection optical system toa state where the liquid is held in the space between both of the stagesand the projection optical system and then to a state where the liquidis held in the space between the other stage and the projection opticalsystem, without going through the process of fully recovering the liquidand supplying the liquid again. Accordingly, it becomes possible tobegin the exposure operation of the substrate on the other stage afterthe exposure operation of the substrate on the one stage has beencompleted within a short period. Further, because the liquid constantlyexists on the image plane side of the projection optical system,generation of water stains (water marks) on the optical members on theimage plane side of the projection optical system can be effectivelyprevented. Further, because the exposure operation of the substrate onthe first stage and the mark detection operation (alignment operation)of the substrate on the second stage by the second mark detectionsystem, and the exposure operation of the substrate on the second stageand the mark detection operation (alignment operation) of the substrateon the first stage by the first mark detection system can each beperformed in parallel, an improvement in the throughput can be expectedwhen comparing the case where the substrate exchange, mark detection(alignment), and exposure operation are performed sequentially, using asingle stage.

According to a sixth aspect of the present invention, there is provideda second exposure apparatus that supplies a liquid to a space between aprojection optical system and a substrate and exposes the substrate withan energy beam via the projection optical system and the liquid, theapparatus comprising: a first stage that can be moved within an area ofa predetermined range including a first area directly below theprojection optical system where the liquid is supplied and a second arealocated on one side of the first area in a first axis direction; asecond stage that can be moved within an area of a predetermined rangeincluding the first area and a third area located on the other side ofthe first area in the first axis direction; and a stage drive systemthat drives the first stage and the second stage, and simultaneouslydrives the first stage and the second stage in the first axis directionwhile one of a state where the first stage and the second stage areclose together in the first axis direction and a state where the firststage and the second stage are in contact in the first axis direction ismaintained, on a transition from a first state in which one stage of thefirst stage and the second stage is positioned at the first area to asecond state in which the other stage is positioned at the first area.

According to this apparatus, when a transition is performed from thefirst state where one stage is positioned at the first area directlybelow the projection optical system where the liquid is supplied to asecond state where the other stage is positioned at the first area, thestage drive system simultaneously drives the first stage and the secondstage in the first axis direction while one of a state where the firststage and the second stage are close together in the first axisdirection and a state where the first stage and the second stage are incontact in the first axis direction is maintained. This allows thetransition from the first state to the second state, in a state wherethe liquid is held in the space between the projection optical systemand at least one stage directly below the projection optical system,while preventing or suppressing the leakage of the liquid from the gapbetween the first stage and the second stage. That is, during the periodafter the exposure operation of the substrate on the first stage via theprojection optical system and the liquid has been performed until themeasurement directly under the projection optical system using thesecond stage begins, it becomes possible to perform the transition froma state where the liquid is held in the space between the first stageand the projection optical system to a state where the liquid is held inthe space between both of the stages and the projection optical systemand then to a state where the liquid is held in the space between thesecond stage and the projection optical system, without going throughthe process of fully recovering the liquid and supplying the liquidagain. Further, the same applies to after the measurement has beencompleted on the second stage until the exposure begins on the firststage. Accordingly, the measurement operation using the second stageafter the exposure operation of the substrate on the first stage hasbeen completed and the exposure operation of the substrate on the firststage after the measurement operation using the second stage has beencompleted can be started within a short period, which can improve thethroughput. Further, because the liquid constantly exists on the imageplane side of the projection optical system, generation of water stains(water marks) on the optical members on the image plane side of theprojection optical system can be effectively prevented. Further, theexposure operation of the substrate using the first stage and themeasurement operation using the second stage can be performed inparallel, depending on the measurement operation.

According to a seventh aspect of the present invention, there isprovided a third exposure apparatus that supplies a liquid to a spacebetween a projection optical system and a substrate and exposes thesubstrate via the projection optical system and the liquid, theapparatus comprising: a first stage that can be moved within an area ofa predetermined range including a first area directly below theprojection optical system where the liquid is supplied and a second arealocated on one side of the first area in a first axis direction; asecond stage that can be moved independent from the first stage withinan area of a predetermined range including the first area and the secondarea; and a stage drive system that drives the first stage and thesecond stage, and simultaneously drives the first stage and the secondstage in a second axis direction intersecting the first axis directionwhile one of a state where the first stage and the second stage areclose together in the second axis direction and a state where the firststage and the second stage are in contact in the second axis directionis maintained, on a transition from a first state in which one stage ofthe first stage and the second stage is positioned at the first area toa second state in which the other stage is positioned at the first area.

According to this apparatus, when a transition is performed from thefirst state where one stage is positioned at the first area directlybelow the projection optical system to which the liquid is supplied tothe second state where the other stage is positioned at the first area,the stage drive system simultaneously drives the first stage and thesecond stage in the second axis direction (the direction intersectingthe first axis direction in which the first area and the second area arearranged) while one of a state where the first stage and the secondstage are close together in the second axis direction and a state wherethe first stage and the second stage are in contact in the second axisdirection is maintained. This allows the transition from the first stateto the second state, in a state where the liquid is held in the spacebetween the projection optical system and at least one stage directlybelow the projection optical system, while preventing or suppressing theleakage of the liquid from the gap between the first stage and thesecond stage. That is, during the period after the exposure operation ofthe substrate on one stage side via the projection optical system andthe liquid has been performed until the exposure operation of thesubstrate on the other stage side via the projection optical system andthe liquid begins, it becomes possible to perform the transition from astate where the liquid is held in the space between one stage and theprojection optical system to a state where the liquid is held in thespace between both of the stages and the projection optical system andthen to a state where the liquid is held in the space between the otherstage and the projection optical system, without going through theprocess of fully recovering the liquid and supplying the liquid again.Accordingly, the exposure operation of the substrate on the other stage,which is performed after the exposure operation of the substrate on theone stage has been completed, can be started within a short period,which allows the throughput to be improved. Further, because the liquidconstantly exists on the image plane side of the projection opticalsystem, generation of water stains (water marks) on the optical memberson the image plane side of the projection optical system can beeffectively prevented.

According to an eighth aspect of the present invention, there isprovided a fourth exposure apparatus that supplies a liquid to a spacebetween a projection optical system and a substrate and exposes thesubstrate via the projection optical system and the liquid, theapparatus comprising: a first stage that can be moved within an areaincluding a first area directly below the projection optical systemwhere the liquid is supplied and an area different from the first area;a second stage that can be moved independent from the first stage withinthe area including the first area and the area different from the firstarea; a stage drive system that drives the first stage and the secondstage, and simultaneously drives the first stage and the second stage ina predetermined direction while a state where the first stage and thesecond stage are close together in the predetermined direction ismaintained, on a transition from a first state in which one stage of thefirst stage and the second stage is positioned at the first area to asecond state in which the other stage is positioned at the first area;and a suppressing member arranged in at least one of the first stage andthe second stage, so as to suppress leakage of the liquid from a gapbetween the stages by being positioned in the gap between the stages onthe transition.

According to this apparatus, when a transition is performed from thefirst state where one stage of the first stage and the second stage thatcan be moved within the area including the first area directly below theprojection optical system and the area different from the first area ispositioned at the first area, to the second state where the other stageis positioned at the first area, because the first stage and the secondstage are in a state close together in the first axis direction and arealso simultaneously driven in the predetermined direction in a statewhere the suppressing member for suppressing liquid leakage arranged inat least one of the first stage and second stage is positioned in thegap between the stages, liquid leakage from between the stages can besuppressed as much as possible.

Further, in a lithography process, by exposing the substrate with theenergy beam using each of the first to fourth exposure apparatus of thepresent invention, the device pattern can be transferred onto thesubstrate with good accuracy, and as a consequence, the productivity ofmicrodevices with high integration can be improved. Accordingly, it canalso be said further from another aspect that the present invention is adevice manufacturing method that includes a lithography process in whichthe substrate is exposed with the energy beam, using any one of thefirst to fourth exposure apparatus of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a configuration of an exposureapparatus related to a first embodiment;

FIG. 2 is a planar view showing a wafer stage unit related to the firstembodiment;

FIG. 3 is a perspective view showing a wafer stage WST1 in FIG. 2;

FIG. 4 is a rough planar view of a liquid supply/drainage mechanism;

FIG. 5 is a block diagram showing the main configuration of a controlsystem of the exposure apparatus in the first embodiment;

FIG. 6 is a view (No. 1) for describing a drive method of two waferstages in a parallel processing operation;

FIG. 7 is a view (No. 2) for describing a drive method of two waferstages in a parallel processing operation;

FIG. 8 is a view (No. 3) for describing a drive method of two waferstages in a parallel processing operation;

FIG. 9 is a view (No. 4) for describing a drive method of two waferstages in a parallel processing operation;

FIG. 10 is a view showing an elastic seal member;

FIG. 11 is a block diagram showing the main configuration of a controlsystem of the exposure apparatus in a second embodiment;

FIG. 12 is a planar view showing a wafer stage unit related to thesecond embodiment;

FIG. 13A is a view (No. 1) for describing a drive method of two waferstages in a parallel processing operation related to the secondembodiment;

FIG. 13B is a view (No. 1) for describing a drive method of two waferstages in a parallel processing operation related to the secondembodiment;

FIG. 14A is a view (No. 2) for describing a drive method of two waferstages in a parallel processing operation related to the secondembodiment;

FIG. 14B is a view (No. 2) for describing a drive method of two waferstages in a parallel processing operation related to the secondembodiment;

FIG. 15A is a view (No. 3) for describing a drive method of two waferstages in a parallel processing operation related to the secondembodiment;

FIG. 15B is a view (No. 3) for describing a drive method of two waferstages in a parallel processing operation related to the secondembodiment;

FIG. 16 is a planar view showing a wafer stage unit related to a thirdembodiment;

FIG. 17A is a view (No. 1) for describing a drive method of a waferstage and a measurement stage in a parallel processing operation relatedto the third embodiment;

FIG. 17B is a view (No. 1) for describing a drive method of a waferstage and a measurement stage in a parallel processing operation relatedto the third embodiment;

FIG. 18A is a view (No. 2) for describing a drive method of a waferstage and a measurement stage in a parallel processing operation relatedto the third embodiment;

FIG. 18B is a view (No. 2) for describing a drive method of a waferstage and a measurement stage in a parallel processing operation relatedto the third embodiment;

FIG. 19A is a view for describing a modified example of a suppressingmember;

FIG. 19B is a view for describing a modified example of a suppressingmember;

FIG. 19C is a view for describing a modified example of a suppressingmember;

FIG. 20 is a planar view showing a wafer stage unit related to a fourthembodiment;

FIG. 21 is a view showing a state where a wafer stage and a measurementstage are close together;

FIG. 22A is a view (No. 1) for describing a drive method of a waferstage and a measurement stage in a parallel processing operation relatedto the fourth embodiment;

FIG. 22B is a view (No. 1) for describing a drive method of a waferstage and a measurement stage in a parallel processing operation relatedto the fourth embodiment;

FIG. 23A is a view (No. 2) for describing a drive method of a waferstage and a measurement stage in a parallel processing operation relatedto the fourth embodiment;

FIG. 23B is a view (No. 2) for describing a drive method of a waferstage and a measurement stage in a parallel processing operation relatedto the fourth embodiment;

FIG. 24 is a view (No. 1) for describing a modified example of thefourth embodiment;

FIG. 25A is a view (No. 2) for describing a modified example of thefourth embodiment;

FIG. 25B is a view (No. 2) for describing a modified example of thefourth embodiment;

FIG. 26 is a flowchart used to explain a device manufacturing methodrelated to the present invention; and

FIG. 27 is a flowchart showing a concrete example related to step 204 inFIG. 26.

BEST MODE FOR CARRYING OUT THE INVENTION A First Embodiment

A first embodiment of the present invention will be described below,referring to FIGS. 1 to 10.

FIG. 1 schematically shows the entire configuration of an exposureapparatus 100 related to the first embodiment. Exposure apparatus 100 isa projection exposure apparatus by the step-and-scan method, that is,the so-called scanning stepper (also called a scanner). Exposureapparatus 100 is equipped with illumination system 10, a reticle stageRST that holds a reticle R serving as a mask, a projection unit PU, awafer stage unit 50 that has wafer stages WST1 and WST2, off-axisalignment systems ALG1 and ALG2, a control system for these componentsor assemblies, and the like. On wafer stages WST1 and WST2, substratesserving as wafers are to be mounted. In FIG. 1, a wafer W1 is mounted onwafer stage WST1, and a wafer W2 is mounted on wafer stage WST2.

As is disclosed in, for example, Kokai (Japanese Unexamined PatentApplication Publication) No. 2001-313250 and its corresponding U.S.Patent Application Publication No. 2003/0025890 description or the like,illumination system 10 is configured including a light source and anilluminance uniformity optical system, which includes an opticalintegrator, and the like. Illumination system 10 also includes a beamsplitter, a relay lens, a variable ND filter, a reticle blind, and thelike (all of which are not shown). In illumination system 10, anillumination light (exposure light) IL illuminates a slit-shapedillumination area set by the reticle blind on reticle R with asubstantially uniform illuminance. In this case, for example, an ArFexcimer laser beam (wavelength: 193 nm) is used as illumination lightIL. Further, as the optical integrator, a fly-eye lens, a rod integrator(an internal reflection type integrator), a diffractive optical elementor the like can be used. As illumination system 10, besides the systemdescribed above, a system having the arrangement disclosed in, forexample, Kokai (Japanese Unexamined Patent Application Publication) No.6-349701, and the corresponding U.S. Pat. No. 5,534,970, may also beemployed. As long as the national laws in designated states or electedstates, to which this international application is applied, permit, theabove disclosures of the Kokai publications, the U.S. Patent applicationpublication description, and the U.S. Patent are incorporated herein byreference.

On reticle stage RST, reticle R on which a circuit pattern or the likeis formed on its pattern surface (the lower surface in FIG. 1) is fixed,for example, by vacuum chucking. Reticle stage RST is finely drivable ormovable in within an XY plane perpendicular to the optical axis ofillumination system 10 (coincides with an optical axis AX of aprojection optical system PL that will be described later) by a reticlestage drive section 11 (not shown in FIG. 1, refer to FIG. 5) thatincludes a linear motor or the like. Reticle stage RST is also drivablein a predetermined scanning direction (in this case, a Y-axis direction,which is the direction orthogonal to the page surface in FIG. 1) at adesignated scanning speed.

The position of reticle stage RST within the stage moving plane isconstantly detected by a reticle laser interferometer (hereinafterreferred to as ‘reticle interferometer’) 116 via a movable mirror 15 ata resolution of, for example, around 0.5 to 1 nm. In actual, on reticlestage RST, a Y movable mirror that has a reflection surface orthogonalto the Y-axis direction and an X movable mirror that has a reflectionsurface orthogonal to an X-axis direction are arranged, andcorresponding to these movable mirrors, a reticle Y interferometer and areticle X interferometer are arranged; however in FIG. 1, such detailsare representatively shown as movable mirror 15 and reticleinterferometer 116. Incidentally, for example, the edge surface ofreticle stage RST may be polished in order to form a reflection surface(corresponds to the reflection surfaces of the X movable mirror and theY movable mirror described above). Further, instead of the reflectionsurface that extends in the X-axis direction used for detecting theposition of reticle stage RST in the scanning direction (the Y-axisdirection in this embodiment), at least one corner cubic mirror (such asa retroreflector) may be used. Of the interferometers reticle Yinterferometer and reticle X interferometer, one of them, such asreticle Y interferometer, is a dual-axis interferometer that has twomeasurement axes, and based on the measurement values of reticle Yinterferometer, the rotation of reticle stage RST in a rotationdirection (a θz direction) around a Z-axis can be measured in additionto the Y position of reticle stage RST.

The measurement values of reticle interferometer 116 are sent to a maincontroller 20 (not shown in FIG. 1, refer to FIG. 5), and based on themeasurement values of reticle interferometer 116, main controller 20computes the position of reticle stage RST in the X, Y, and θzdirections and also controls the position (and velocity) of reticlestage RST by controlling reticle stage drive section 11 based on thecomputation results.

Above reticle R, reticle alignment detection systems RAa and RAb inpairs, each consisting of a TTR (Through The Reticle) alignment systemthat uses light of the exposure wavelength to observe a reticle mark onreticle R and a corresponding fiducial mark on a fiducial mark plate atthe same time via projection optical system PL, are arranged in theX-axis direction at a predetermined distance. As such reticle alignmentdetection systems RAa and RAb, a system having a structure similar tothe one disclosed in, for example, Kokai (Japanese Unexamined PatentApplication Publication) No. 7-176468 and the corresponding U.S. Pat.No. 5,646,413 or the like is used. As long as the national laws indesignated states (or elected states), to which this internationalapplication is applied, permit, the above disclosures of the Kokaipublication and the U.S. Patent are incorporated herein by reference.

Projection unit PU is arranged below reticle stage RST in FIG. 1.Projection unit PU is configured including a barrel 40, and projectionoptical system PL consisting of a plurality of optical elements held ina predetermined positional relation within barrel 40. As projectionoptical system PL, a dioptric system is used, consisting of a pluralityof lenses (lens elements) that share an optical axis AX in the Z-axisdirection. Projection optical system PL is, for example, a both sidetelecentric dioptric system that has a predetermined projectionmagnification (such as one-quarter, one-fifth, or one-eighth times) isused. Therefore, when illumination light IL from illumination system 10illuminates the illumination area on reticle R, a reduced image of thecircuit pattern within the illumination area of reticle R (a partialreduced image of the circuit pattern) is formed on the wafer whosesurface is coated with a resist (a photosensitive agent) by illuminationlight IL that has passed through reticle R, via projection unit PU(projection optical system PL).

In exposure apparatus 100 of the embodiment, because exposure isperformed applying the immersion method (to be described later), thenumerical aperture NA substantially increases which makes the opening onthe reticle side larger. Therefore, in a dioptric system consisting onlyof lenses, it becomes difficult to satisfy the Petzval condition, whichtends to lead to an increase in the size of the projection opticalsystem. In order to prevent such an increase in the size of theprojection optical system, a catodioptric system that includes mirrorsand lenses may also be used.

Further, in the embodiment, a liquid supply/drainage system 32 forlocally supplying a liquid in the space between a lens 91 constitutingprojection optical system PL closest to the image plane side (the waferside) (hereinafter also referred to as a ‘tip lens’) and the wafer onwafer stage WST1 or WST2 (or between tip lens 91 and wafer stage WST1 orWST2) In FIG. 1, a nozzle constituting this liquid supply/drainage unitis representatively shown as liquid supply/drainage system 32. Thearrangement or the like of liquid supply/drainage system 32 will bedescribed later in the description.

Wafer stage unit 50 is equipped with a base platform 12, wafer stagesWST1 and WST2 arranged above the upper surface of base platform 12, aninterferometer system 118 (refer to FIG. 5) that includesinterferometers 16 and 18 for measuring the positions of wafer stagesWST1 and WST2, and a wafer stage drive section 124 (refer to FIG.5) fordriving wafer stages WST1 and WST2.

On the bottom surface of wafer stages WST1 and WST2, non-contactbearings (not shown) such as, for example, vacuum preload air bearings(hereinafter referred to as ‘air pads’) are arranged in a plurality ofareas, and by the static pressure of the pressurized air blowing outfrom the air pads toward the upper surface of base platform 12, waferstages WST1 and WST2 are supported by levitation in a non-contact mannerabove the upper surface of base platform 12 via a clearance of aroundseveral μm. Further, wafer stages WST1 and WST2 are configured drivableor movable in a two-dimensional direction, individually in the X-axisdirection (the lateral direction of the page surface in FIG. 1) and theY-axis direction (the orthogonal direction of the page surface in FIG.1), by wafer stage drive section 124.

On base platform 12, as is shown in the planar view in FIG. 2, X-axislinear guides 86 and 87 in pairs, serving as an X stator extending inthe X-axis direction, are arranged at a predetermined distance in theY-axis direction. X-axis linear guides 86 and 87 are each configured,for example, of a magnetic pole unit that incorporates a permanentmagnet group consisting of a plurality of sets of an N-pole magnet andan S-pole magnet alternately arranged along the X-axis direction at apredetermined distance. Above X-axis linear guides 86 and 87, twosliders each, sliders 82, 84 and sliders 83, 85 are arranged in a stateenclosing the corresponding X-axis linear guides 86 and 87 from above ina non-contact manner. More specifically, the four sliders in total, 82,84, 83, and 85 have a cross-sectional shape resembling the letter U soas to enclose the corresponding X-axis linear guides 86 and 87 fromabove and from the side, and the sliders are supported by levitationwith respect to the corresponding X-axis linear guides 86 and 87, viathe air pads (not shown) via a clearance of (e.g.) around several μm.Sliders 82, 84, 83, and 85 are each configured by an armature unit thatincorporates a plurality of armature coils arranged along the X-axisdirection at a predetermined distance. More specifically, in theembodiment, sliders 82 and 84 consisting of armature units and X-axislinear guide 86 consisting of the magnetic pole unit constitute movingmagnet type X-axis linear motors. Similarly, sliders 83 and 85 andX-axis linear guide 87 constitute moving magnet type X-axis linearmotors. In the description below, the four X-axis linear motors willeach be appropriately referred to as X-axis linear motor 82, X-axislinear motor 84, X-axis linear motor 83, and X-axis linear motor 85,using the same reference numerals as the sliders 82, 84, 83, and 85configuring each of the movers.

Of the four X-axis linear motors referred to above, the sliders thatconfigure the two X-axis linear motors, 82 and 83, are fixed to bothends in the longitudinal direction of a Y-axis linear guide 80 servingas a Y stator extending in the Y-axis direction. Further, the slidersthat configure the remaining two X-axis linear motors, 84 and 85, arefixed to both ends of a Y-axis linear guide 81 serving as a Y statorextending in the Y-axis direction. Accordingly, Y-axis linear guides 80and 81 are each driven along the X-axis by the pair of X-axis linearmotors 82 and 83 and by the pair of X-axis linear motors 84 and 85,respectively.

Y-axis linear guides 80 and 81 are each configured, for example, by anarmature unit that incorporates armature coils arranged along the Y-axisdirection at a predetermined distance.

One of the Y-axis linear guides, Y-axis linear guide 81, is arranged inan inserted state in an opening formed in wafer stage WST1. Inside theopening referred to above of wafer stage WST1, for example, a magneticpole unit that has a permanent magnet group consisting of a plurality ofsets of an N-pole magnet and an S-pole magnet alternately arranged alongthe Y-axis direction at a predetermined distance is arranged. And, themagnetic pole unit and Y-axis linear guide 81 constitute a moving magnettype Y-axis linear motor that drives wafer stage WST1 in the Y-axisdirection. Similarly, the other Y-axis linear guide, Y-axis linear guide80, is arranged in an inserted state in an opening formed in wafer stageWST2. Inside the opening referred to above of wafer stage WST2, forexample, a magnetic pole unit similar to the one arranged in wafer stageWST1 side is arranged. And, the magnetic pole unit and Y-axis linearguide 80 constitute a moving magnet type Y-axis linear motor that driveswafer stage WST2 in the Y-axis direction. In the description below, theY-axis linear motors will each be appropriately referred to as Y-axislinear motor 81 and Y-axis linear motor 80, using the same referencenumerals as the linear guides 81 and 80 configuring each of the stators.

In the embodiment, wafer stage drive section 124 shown in FIG. 5 isconfigured including X-axis linear motors 82 to 85 and Y-axis linearmotors 80 and 81. Each of the linear motors described above thatconfigure wafer stage drive section 124 operate under the control ofmain controller 20 shown in FIG. 5.

By slightly changing the thrust generated by the pair of X-linear motors84 and 85 (or 82 and 83), yawing control of wafer stage WST1 (or WST2)becomes possible.

In the embodiment, wafer stages WST1 and WST2 are each shown as amonolithic stage. In actual, however, wafer stages WST1 and WST2 areeach equipped with a stage main body driven by Y-axis linear motors 81and 80, and a wafer table mounted on the wafer stage main body via aZ-leveling drive mechanism (such as a voice coil motor or the like) thatcan be finely driven or moved relatively in the Z-axis direction and inthe rotational directions around the X-axis (θx direction) and theY-axis (θy direction).

On wafer stage WST1 (or to be more precise, on the wager table), as isshown in FIG. 1, a wafer holder H1 that holds wafer W1 by vacuum suctionor the like is arranged. As it can be seen from the perspective view inFIG. 3, wafer holder H1 has a roughly square shape main body section 70in a planar view (when viewed from above), and four auxiliary plates 72a to 72 d arranged in the periphery of the area where wafer W1 is to bemounted so that they overlap main body section 70 from above. Thesurfaces of such auxiliary plates 72 a to 72 d are arranged so that theyare substantially the same height as the surface of wafer W1.Incidentally, auxiliary plates 72 a to 72 d may consist of a singlemember. Further, there may be a step formed between the wafer surfaceand the auxiliary plate surface, as long as liquid Lq can be held on theimage plane side of projection optical system PL.

On the upper surface of wafer stage WST1, an X movable mirror 17X thathas a reflection surface orthogonal to the X-axis on one end in theX-axis direction (the +X side end) is arranged extending in the Y-axisdirection, and a Y movable mirror 17Y that has a reflection surfaceorthogonal to the Y-axis on one end in the Y-axis direction (the +Y sideend) is arranged extending in the X-axis direction. As is shown in FIG.2, interferometer beams (measurement beams) from the interferometersthat configure interferometer system 118 (to be described later, referto FIG. 5) are incident on each reflection surface of movable mirrors17X and 17Y, and by each of the interferometers receiving the reflectionbeams, displacement from the reference position (normally, a fixedmirror is arranged on the side surface of projection unit PU or on theside surface of alignment system ALG1, which is to be the referenceplane) of the reflection surface of each movable mirror is measured.Accordingly, the two-dimensional position of wafer stage WST1 ismeasured. It is desirable to also keep the upper surface of movablemirrors 17X and 17Y substantially the same height (flush) as wafer W1.

As is shown in FIG. 3, a gap D exists between each of the auxiliaryplates 72 a to 72 d and wafer W1. The size of the gap is set from 0.1 mmto 1 mm and under. In addition, a notch (a V-shaped cut) is formed in apart of wafer W; however, the notch is omitted in the drawings since thesize of the notch is also around 1 mm.

Further, a circular opening is formed in a part of auxiliary plate 72 a,and a fiducial mark plate FM1 is embedded into the opening. The surfaceof fiducial mark plate FM1 is to be on the same plane as auxiliary plate72 a. On the surface of fiducial mark plate FM1, at least a firstfiducial mark in pairs for reticle alignment, a second fiducial markdetected by alignment system ALGL1 in the manner described later (noneof which are shown), and the like are formed.

On wafer stage WST2 (or to be more precise, on the wafer table), a waferholder H2 that holds wafer W2 by vacuum suction or the like is arranged,as is shown in FIG. 1. Wafer holder H2 has an arrangement similar towafer holder H1 previously described. Accordingly, in the circularopening formed in a part of an auxiliary plate configuring wafer holderH2, a fiducial mark plate FM2 is embedded (not shown in FIG. 1, refer toFIG. 2).

Further, on the upper surface of wafer stage WST2, an X movable mirror117X that has a reflection surface orthogonal to the X-axis on one endin the X-axis direction (the −X side end) is arranged extending in theY-axis direction, and a Y movable mirror 117Y that has a reflectionsurface orthogonal to the Y-axis on one end in the Y-axis direction (the+Y side end) is arranged extending in the X-axis direction. As is shownin FIG. 2, interferometer beams (measurement beams) from theinterferometers that configure interferometer system 118 (to bedescribed later, refer to FIG. 5) are incident on each reflectionsurface of movable mirrors 117X and 117Y, and by each of theinterferometers receiving the reflection beams, displacement from thereference position of the reflection surface of each movable mirror ismeasured. Accordingly, the two-dimensional position of wafer stage WST2is measured.

Incidentally, the end surfaces of wafer stages WST1 and WST2 can bemirror-polished so as to make reflection surfaces (corresponding to thereflection surfaces of movable mirrors 17X, 17Y, 117X, and 117Ypreviously described).

Further, on the surface on the side of wafer stages WST1 and WST2 thatface each other, e.g. the −X side surface of wafer stage WST1, a sealmember 93 is applied covering the entire surface as is shown in FIG. 10.As such seal member 93, for example, an elastic seal member made offluorine-contained rubber or the like is used.

Instead of applying seal member 93 to the −X side surface of wafer stageWST1, seal member 93 can be applied to the +X side surface of waferstage WST2, or seal member 93 can be applied to both the −X side surfaceof wafer stage WST1 and the +X side surface of wafer stage WST2.

Referring back to FIG. 1, on both sides of projection unit PU on the +Xside and the −X side at positions equally apart, off-axis alignmentsystems (hereinafter simply referred to as ‘alignment systems’) ALGL1and ALG2 referred to earlier are disposed. In actual, alignment systemsALGL1 and ALG2 are attached to a holding member that holds projectionunit PU. As alignment systems ALG1 and ALG2, for example, a sensor of anFIA (Field Image Alignment) system based on an image-processing methodis used. This sensor irradiates a broadband detection beam that does notexpose the resist on the wafer on a target mark, picks up the images ofthe target mark formed on the photodetection surface by the reflectionlight from the target mark and an index (not shown; an index pattern onan index plate arranged inside alignment systems ALGL1 and ALG2) with apick-up device (such as a CCD), and outputs the imaging signals.Incidentally, alignment systems ALGL1 and ALG2 are not limited to theFIA system, and it is a matter of course that an alignment sensor thatirradiates a coherent detection light on a target mark and detects thescattered light or diffracted light generated from the target mark, or asensor that detects two diffracted lights (e.g. diffracted lights of thesame order, or diffracted lights diffracting in the same direction)generated from the target mark by making them interfere with each othercan be used independently, or appropriately combined.

In the embodiment, alignment system ALG1 is used for measuring theposition of alignment marks formed on wafer W1, fiducial marks formed onfiducial mark plate FM1, and the like. Further, alignment system ALG2 isused for measuring the position of alignment marks formed on wafer W2,fiducial marks formed on fiducial mark plate FM2, and the like.

Information from these alignment systems ALG1 and ALG2 is to be suppliedto main controller 20, as is shown in FIG. 5.

Next, the arrangement and the like of interferometer system 118 will bedescribed, referring to FIG. 2. As is shown in FIG. 2, interferometersystem 118 has three Y-axis interferometers, 46, 48, and 44 whosemeasurement axes are BI2Y, BI3Y, and BI1Y. The measurement axes areparallel to the Y-axis, and respectively pass through the detectioncenter of projection optical system PL (optical axis AX), the detectioncenter of alignment system ALG1, and the detection center of alignmentsystem ALG2. Interferometer system 118 also has two X-axisinterferometers, 16 and 18 whose measurement axes are BI1X and BI2X.These measurement axes are parallel to the X-axis, and respectively jointhe detection center of projection optical system PL (optical axis AX)and the detection center of alignment system ALG1, and the detectioncenter of projection optical system PL (optical axis AX) and thedetection center of alignment system ALG2.

In this case, when wafer stage WST1 is in the area (a first area) in thevicinity of the position directly under the optical axis of projectionoptical system PL and exposure of the wafer on wafer stage WST1 is to beperformed, the position of wafer stage WST1 is controlled by X-axisinterferometer 18 and Y-axis interferometer 46. In the descriptionbelow, the coordinate system set by the measurement axes of X-axisinterferometer 18 and Y-axis interferometer 46 will be referred to as afirst exposure coordinate system.

Further, when wafer stage WST2 is in the first area and exposure of thewafer on wafer stage WST2 is to be performed, the position of waferstage WST1 is controlled by X-axis interferometer 16 and Y-axisinterferometer 46. In the description below, the coordinate system setby the measurement axes of X-axis interferometer 16 and Y-axisinterferometer 46 will be referred to as a second exposure coordinatesystem.

Further, when wafer stage WST1 is in the area (a second area) in thevicinity of the position directly under the detection center ofalignment system ALG1 and detection of alignment marks formed on thewafer on wafer stage WST1 such as wafer alignment (to be describedlater) is to be performed, the position of wafer stage WST1 iscontrolled by X-axis interferometer 18 and Y-axis interferometer 48. Inthe description below, the coordinate system set by the measurement axesof X-axis interferometer 18 and Y-axis interferometer 48 will bereferred to as a first alignment coordinate system.

Further, when wafer stage WST2 is in the area (a third area) in thevicinity of the position directly under the detection center ofalignment system ALG2 and detection of alignment marks formed on thewafer on wafer stage WST2 such as wafer alignment (to be describedlater) is to be performed, the position of wafer stage WST2 iscontrolled by X-axis interferometer 16 and Y-axis interferometer 44. Inthe description below, the coordinate system set by the measurement axesof X-axis interferometer 16 and Y-axis interferometer 44 will bereferred to as a second alignment coordinate system.

As is obvious from the description above, in the embodiment, theinterferometer beams from X-axis interferometers 18 and 16 constantlyirradiate movable mirrors 17X and 117X of wafer stages WST1 and WST2,respectively, in the entire moving range of wafer stages WST1 and WST2.Accordingly, for the X-axis direction, the position of wafer stages WST1and WST2 is controlled by X-axis interferometers 18 and 16 in any case,such as when exposure is performed using projection optical system PLand also when alignment systems ALGL1 and ALG2 are used. Such X-axisinterferometers 18 and 16 are both multi-axis interferometers that haveat least three measurement axes that are separate in the Y-axisdirection and the Z-axis direction, and the output values of eachoptical axis can be measured independently. Accordingly, with these Xinterferometers 18 and 16, other than measuring the position of waferstages WST1 and WST2 in the X-axis direction, the rotation amount aroundthe Y-axis (rolling amount) and the rotation amount around the Z-axis(yawing amount) can also be measured.

Further, Y-axis interferometers 44, 46, and 48 are dual-axisinterferometers each having two optical axes that are separate, forexample, in the Z-axis direction, and the output values of each opticalaxis can be measured independently. Accordingly, with these Y-axisinterferometers 44, 46, and 48, other than measuring the position ofwafer stages WST1 and WST2 in the Y-axis direction, the rotation amountaround the X-axis (pitching amount) can also be measured.

Further, the multi-axis interferometers described above may detectpositional information related to the optical axis direction (the Z-axisdirection) of projection optical system PL, by irradiating laser beamson a reflection surface arranged on the frame on which projectionoptical system PL is mounted (not shown), via reflection surfacesarranged on wafer stages WST1 and WST2 at an inclination of 45°.

Next, details on liquid supply/drainage system 32 will be described,referring to FIG. 4. Liquid supply/drainage system 32 is equipped with aliquid supply unit 5, a liquid recovery unit 6, supply pipes 21, 22, 27,and 28 connecting to liquid supply unit 5 and recovery pipes 23, 24, 29,30 connecting to liquid recovery unit 6 and the like.

Liquid supply unit 5 is configured to include a liquid tank, acompression pump, a temperature control unit, a plurality of valves forcontrolling the supply/stop of the liquid to supply pipes 21, 22, 27,and 28, and the like. As the valves referred to above, flow controlvalves are preferably used so that not only the supply/stop of theliquid but also the flow rate can be adjusted. The temperature controlunit adjusts the temperature of the liquid within the liquid tank sothat the temperature of the liquid is about the same level as thetemperature within the chamber (not shown) where the exposure apparatusmain body constituted by projection unit PU and the like are housed.

One end of supply pipe 21 connects to liquid supply unit 5. The otherend branches into three sections where on each end, supply nozzles 21 a,21 b, and 21 c consisting of a tapered nozzle are respectively formed(arranged). The tip of these supply nozzles 21 a, 21 b, and 21 c arelocated in the vicinity of tip lens 91 (refer to FIG. 1) previouslydescribed, and are arranged in the X-axis direction at a predetermineddistance and also close to the +Y side of an exposure area IA (an areaon the image plane conjugate with the illumination area on the slitpreviously described). The supply nozzles are arranged symmetrically,with supply nozzle 21 a in the center and supply nozzles 21 b and 21 con both sides.

One end of supply pipe 22 connects to liquid supply unit 5. The otherend branches into three sections where on each end, supply nozzles 22 a,22 b, and 22 c consisting of a tapered nozzle are respectively formed(arranged). The tip of these supply nozzles 22 a, 22 b, and 22 c arelocated in the vicinity of tip lens 91, and are arranged in the X-axisdirection at a predetermined distance and also close to the −Y side ofexposure area IA. In this case, supply nozzles 22 a, 22 b, and 22 c arearranged facing supply nozzles 21 a, 21 b, and 21 c, with exposure areaIA in between.

One end of supply pipe 27 connects to liquid supply unit 5. The otherend has a supply nozzle 27 a consisting of a tapered nozzle formed(arranged). The tip of supply nozzle 27 a is located in the vicinity oftip lens 91, and is arranged close to the −X side of exposure area IA.

One end of supply pipe 28 connects to liquid supply unit 5. The otherend has a supply nozzle 28 a consisting of a tapered nozzle formed(arranged). The tip of supply nozzle 28 a is located in the vicinity oftip lens 91, and is arranged close to the +X side of exposure area IAand also faces supply nozzle 27 a, with exposure area IA in between.

Incidentally, the liquid tank, the compression pump, the temperatureadjustment unit, the valves, and the like do not all have to be equippedin exposure apparatus 100, and at least a part of such parts may besubstituted by the equipment available in the factory where exposureapparatus 100 is installed.

Liquid recovery unit 6 is configured to include a liquid tank and asuction pump, and a plurality of valves for controlling therecovery/stop of the liquid via recovery pipes 23, 24, 29, and 30, andthe like. As the valves, flow control valves are preferably usedcorresponding to the valves used in the liquid supply unit 5.

One end of recovery pipe 23 connects to liquid recovery unit 6. Theother end branches into two sections where on each end, recovery nozzles23 a and 23 b consisting of a widened nozzle are respectively formed(arranged). In this case, recovery nozzles 23 a and 23 b are arrangedalternately in between supply nozzles 22 a to 22 c. The tip of recoverynozzles 23 a and 23 b and the tip of supply nozzles 22 a, 22 b, and 22 care arranged substantially collinear on a line parallel to the X-axis.

One end of recovery pipe 24 connects to liquid recovery unit 6. Theother end branches into two sections where on each end, recovery nozzles24 a and 24 b consisting of a widened nozzle are respectively formed(arranged). In this case, recovery nozzles 24 a and 24 b are arrangedalternately in between supply nozzles 21 a to 21 c and also facerecovery nozzles 23 a and 23 b, with exposure area IA in between. Thetip of recovery nozzles 24 a and 24 b and the tip of supply nozzles 21a, 21 b, and 21 c are arranged substantially collinear on a lineparallel to the X-axis.

One end of recovery pipe 29 connects to liquid recovery unit 6. Theother end branches into two sections where on each end, recovery nozzles29 a and 29 b consisting of a widened nozzle are respectively formed(arranged). Recovery nozzles 29 a and 29 b are arranged with supplynozzle 28 a in between. The tip of recovery nozzles 29 a and 29 b andthe tip of supply nozzle 28 a are arranged substantially collinear on aline parallel to the Y-axis.

One end of recovery pipe 30 connects to liquid recovery unit 6. Theother end branches into two sections where on each end, recovery nozzles30 a and 30 b consisting of a widened nozzle are respectively formed(arranged). Recovery nozzles 30 a and 30 b are arranged with supplynozzle 27 a in between, and also face recovery nozzles 29 a and 29 b,with exposure area IA in between. The tip of recovery nozzles 30 a and30 b and the tip of supply nozzle 27 a are arranged substantiallycollinear on a line parallel to the Y-axis.

Incidentally, the tank for recovering the liquid, the suction pump, thevalves, and the like do not all have to be equipped in exposureapparatus 100, and at least a part of such parts may be substituted bythe equipment available in the factory where exposure apparatus 100 isinstalled.

In the embodiment, as the liquid, ultra pure water (hereinafter, it willsimply be referred to as ‘water’ besides the case when specifying isnecessary) that transmits the ArF excimer laser beam (light with awavelength of 193 nm) is to be used. Ultra pure water can be obtained inlarge quantities at a semiconductor manufacturing plant or the like, andit also has an advantage of having no adverse effect on the photoresiston the wafer or to the optical lenses. Further, ultra pure water has noadverse effect on the environment as well as an extremely lowconcentration of impurities, therefore, cleaning action on the surfaceof the wafer and the surface of tip lens 91 can be anticipated.

Refractive index n of the water is said to be around 1.44. In the waterthe wavelength of illumination light IL is 193 nm×1/n, shorted to around134 nm.

Liquid supply unit 5 and liquid recovery unit 6 both have a controller,and the controllers operate under the control of main controller 20(refer to FIG. 5). For example, when wafer W1 (or wafer W2) is moved ina direction shown by a solid arrow A in FIG. 4 (−Y direction), accordingto instructions from main controller 20, the controller of liquid supplyunit 5 opens the valve connected to supply pipe 21 to a predetermineddegree and completely closes the other valves so as to supply the waterin the space between tip lens 91 and wafer W1 (or W2) toward the −Ydirection via supply nozzles 21 a to 21 c arranged in supply pipe 21.Further, when the water is supplied, according to instructions from maincontroller 20, the controller of liquid recovery unit 6 opens the valveconnected to recovery pipe 23 to a predetermined degree and completelycloses the other valves so that the water is recovered into liquidrecovery unit 6 from the space between tip lens 91 and wafer W1 (or W2)via recovery nozzles 23 a and 23 b. During the supply and recoveryoperations, main controller 20 gives orders to liquid supply unit 5 andliquid recovery unit 6 so that the amount of water supplied to the spacebetween tip lens 91 and wafer W1 (or W2) toward the −Y direction fromsupply nozzles 21 a to 21 c constantly equals the amount of waterrecovered via recovery nozzles 23 a and 23 b. Accordingly, a constantamount of water Lq (refer to FIG. 1) is held or retained in the spacebetween tip lens 91 and wafer W1 (or W2). In this case, water Lq held inthe space between tip lens 91 and wafer W1 (or W2) is constantlyreplaced.

Further, when wafer W1 (or wafer W2) is moved in a direction shown by adotted arrow A′ in FIG. 4 (+Y direction), according to instructions frommain controller 20, the controller of liquid supply unit 5 opens thevalve connected to supply pipe 22 to a predetermined degree andcompletely closes the other valves so as to supply the water in thespace between tip lens 91 and wafer W1 (or W2) toward the +Y directionvia supply nozzles 22 a to 22 c arranged in supply pipe 22. Further,when the water is supplied, according to instructions from maincontroller 20, the controller of liquid recovery unit 6 opens the valveconnected to recovery pipe 24 to a predetermined degree and completelycloses the other valves so that the water is recovered into liquidrecovery unit 6 from the space between tip lens 91 and wafer W1 (or W2)via recovery nozzles 24 a and 24 b. During the supply and recoveryoperations, main controller 20 gives orders to liquid supply unit 5 andliquid recovery unit 6 so that the amount of water supplied to the spacebetween tip lens 91 and wafer W1 (or W2) toward the +Y direction fromsupply nozzles 22 a to 22 c constantly equals the amount of waterrecovered via recovery nozzles 24 a and 24 b. Accordingly, a constantamount of water Lq (refer to FIG. 1) is held in the space between tiplens 91 and wafer W1 (or W2). In this case, water Lq held in the spacebetween tip lens 91 and wafer W1 (or W2) is constantly replaced.

As is described above, in the embodiment, a group of supply nozzles anda group of recovery nozzles that are grouped together is arranged onboth one side and the other side of the Y-axis direction with exposurearea IA in between. Therefore, in the case the wafer is moved in eitherthe +Y direction or in the −Y direction, the space between wafer W1 (orW2) and tip lens 91 continues to be filled stably with the water. Thatis, in both the so-called plus-scan and the minus scan, the water can bestably held in the space between the wafer and tip lens 91.

Further, because the water flows over wafer W1 (or W2), in the caseforeign particles (including scattered particles from the resist) adhereon wafer W1 (or wafer W2), the water can remove such foreign particles.Further, because liquid supply unit 5 supplies water whose temperatureis adjusted to a predetermined temperature and the water is constantlyreplaced, even if illumination light IL is irradiated on wafer W1 (orW2) on exposure, heat exchange is performed between the wafer and thewater flowing over the wafer, which can suppress temperature increase ofthe wafer surface. Further, in the embodiment, because the water flowsin the same direction as the moving direction of the wafer, the liquidthat has absorbed the foreign particles or heat can be recovered withoutthe liquid staying in the exposure area directly under the tip lens.

Further, when wafer W1 (or wafer W2) is moved in a direction shown by asolid arrow B in FIG. 4 (+X direction), according to instructions frommain controller 20, the controller of liquid supply unit 5 opens thevalve connected to supply pipe 27 to a predetermined degree andcompletely closes the other valves so as to supply the water in thespace between tip lens 91 and wafer W1 (or W2) toward the +X directionvia supply nozzle 27 a arranged in supply pipe 27. Further, when thewater is supplied, according to instructions from main controller 20,the controller of liquid recovery unit 6 opens the valve connected torecovery pipe 29 to a predetermined degree and completely closes theother valves so that the water is recovered into liquid recovery unit 6from the space between tip lens 91 and wafer W1 (or W2) via recoverynozzles 29 a and 29 b. During the supply and recovery operations, maincontroller 20 gives orders to liquid supply unit 5 and liquid recoveryunit 6 so that the amount of water supplied to the space between tiplens 91 and wafer W1 (or W2) from supply nozzle 27 a constantly equalsthe amount of water recovered via recovery nozzles 29 a and 29 b.Accordingly, a constant amount of water Lq (refer to FIG. 1) is held inthe space between tip lens 91 and wafer W1 (or W2). In this case, waterLq held in the space between tip lens 91 and wafer W1 (or W2) isconstantly replaced.

Further, when wafer W1 (or wafer W2) is moved in a direction shown by adotted arrow B′ in FIG. 4 (−X direction), according to instructions frommain controller 20, the controller of liquid supply unit 5 opens thevalve connected to supply pipe 28 to a predetermined degree andcompletely closes the other valves so as to supply the water in thespace between tip lens 91 and wafer W1 (or W2) toward the −X directionvia supply nozzle 28 a arranged in supply pipe 28. Further, when thewater is supplied, according to instructions from main controller 20,the controller of liquid recovery unit 6 opens the valve connected torecovery pipe 30 to a predetermined degree and completely closes theother valves so that the water is recovered into liquid recovery unit 6from the space between tip lens 91 and wafer W1 (or W2) via recoverynozzles 30 a and 30 b. During the supply and recovery operations, maincontroller 20 gives orders to liquid supply unit 5 and liquid recoveryunit 6 so that the amount of water supplied to the space between tiplens 91 and wafer W1 (or W2) toward the +Y direction from supply nozzle28 a constantly equals the amount of water recovered via recoverynozzles 30 a and 30 b. Accordingly, a constant amount of water Lq (referto FIG. 1) is held in the space between tip lens 91 and wafer W1 (orW2). In this case, water Lq held in the space between tip lens 91 andwafer W1 (or W2) is constantly replaced.

In the manner described above, as in the case of moving wafer W1 (or W2)in the Y-axis direction, in the case of moving the wafer in either the+X direction or the −X direction, the space between the wafer and tiplens 91 continues to be filled stably with the water. Accordingly,during the so-called stepping operation between shots, the water can becontinuously held in the space between the wafer and tip lens 91.

In the description above, the case has been described in which the wateris held in the space between the wafer and the tip lens. However, as ispreviously described, because the wafer surface and the surface of waferholders H1 and H2 are substantially flush, even in the case wafer holderH1 (or H2) is located at a position corresponding to exposure area IAdirectly under projection unit PU, the water is held in the spacebetween tip lens 91 and wafer holder H1 (or H2), or in other words, theauxiliary plates previously described, as in the description above.Further, during the stepping operation, in the case the water can beheld in the space between the wafer and tip lens 91, the water supplyand recovery can be stopped.

In addition to the nozzles that supply and recover the water from theX-axis direction or the Y-axis direction, for example, nozzles thatsupply and recover the water from an oblique direction can also bearranged.

Further, supply nozzles 21 a to 21 c, 22 a to 22 c, 27 a, and 28 a cancontinue to supply liquid Lq while recovery nozzles 23 a, 23 b, 24 a, 24b, 29 a, 29 b, 30 a, and 30 b continue to recover liquid Lq, regardlessof the moving direction of the wafer.

Further, the liquid supply/drainage system is not limited to thearrangement shown in FIG. 4 described above, and various arrangementscan be applied as long as an immersion area can be formed on the imageplane side of projection optical system PL.

In exposure apparatus 100 of the embodiment, further in the holdingmember that holds projection unit PU (not shown), a multiple point focalposition detection system based on an oblique method constituted by anirradiation system 90 a (not shown in FIG. 1, refer to FIG. 5) and aphotodetection system 90 b (not shown in FIG. 1, refer to FIG. 5),similar to the one disclosed in, for example, Kokai (Japanese PatentUnexamined Application Publication) No. 6-283403 and the correspondingU.S. Pat. No. 5,448,332, is arranged. Irradiation system 90 a has alight source whose on/off is controlled by main controller 20 in FIG. 5,and emits imaging beams toward the imaging plane of projection opticalsystem PL so as to form a large number of pinholes or slit images. Theemitted beams are irradiated on the wafer surface from an obliquedirection against optical axis AX via a prism (not shown, a part of theoptical system in irradiation system 90 a) arranged on the barrel ofprojection unit PU. Meanwhile, the beams of the imaging beams reflectedoff the wafer surface are reflected by another prism (not shown, a partof the optical system in photodetection system 90 b) arranged on thebarrel of projection unit PU, and are received by a photodetectionelement in photodetection system 90 b.

Defocus signals, which are an output of photodetection system 90 b offocal position detection system (90 a, 90 b), are sent to maincontroller 20. On scanning exposure (to be described later) or the like,main controller 20 computes the Z position of the wafer surface and theθx and θy rotations based on defocus signals such as the S-curve signalfrom photodetection system 90 b, and controls the movement of waferstages WST1 and WST2 in the Z-axis direction and the inclination in atwo-dimensional direction (that is, rotation in the θx and θy direction)via wafer stage drive section 124 so that the difference between the Zposition of the wafer surface and the θx and θy rotations that have beencalculated and their target values become zero, or in other words,defocus equals zero. And, by such control, main controller 20 performsauto-focusing (automatic focusing) and auto-leveling in which theimaging plane of projection optical system PL and the surface of thewafer are made to substantially coincide with each other within theirradiation area (the area optically conjugate with the illuminationarea described earlier) of illumination light IL. As long as thenational laws in designated states or elected states, to which thisinternational application is applied, permit, the above disclosures ofKokai (Japanese Patent Unexamined Application Publication) No. 6-283403and the corresponding U.S. patent are incorporated herein by reference.

The focal position detection system can be a system that detectspositional information of the wafer surface via a liquid, or it can be asystem that performs detection without going through the liquid.Further, the focal position detection system is not limited to thesystem that detects positional information of the wafer surface on theimage plane side of projection optical system PL, and it can be a systemthat detects positional information of the wafer surface at a positionaway from projection optical system PL.

FIG. 5 shows a main arrangement of a control system of exposureapparatus 100 of the embodiment. The control system is mainly composedof main controller 20, which is made up of a microcomputer (or aworkstation) or the like having overall control over the entireapparatus.

Next, the operation of each section on exposure in exposure apparatus100 of the embodiment will be described. In the following description,as is shown in FIG. 2, the case when exposure is performed on the waferstage WST1 side will be described.

On starting the exposure operation, main controller 20 moves wafer stageWST1 to a scanning starting position (acceleration starting position)for exposure of the first shot area on wafer W by controlling X-axislinear motors 84 and 85 and Y-axis linear motor 81 while monitoring themeasurement values of interferometers 18 and 46, based on the results ofwafer alignment performed in advance such as, for example, EnhancedGlobal Alignment (EGA). In this exposure sequence, the position of waferstage WST1 is controlled on the first exposure coordinate system.

Next, main controller 20 begins the relative scanning of reticle R(reticle stage RST) and wafer W1 (wafer stage WST1) in the Y-axisdirection. On this relative scanning, main controller 20 controls bothreticle stage drive section 11 and Y-axis linear motor 81 (and X-axislinear motors 84 and 85), while monitoring the measurement values ofinterferometers 18 and 46 and reticle interferometer 116 previouslydescribed.

Then, when both stages RST and WST1 reach their target scanning speed,main controller 20 gives instructions to the light source (the ArFexcimer laser unit, not shown) to start pulse emission. And, when bothstages, RST and WST, reach a constant speed synchronous state,illumination light IL (ultraviolet pulse light) from illumination system10 begins to illuminate the pattern area of reticle R, and scanningexposure begins. Pulse emission of the light source starts prior to thebeginning of the scanning exposure as is described above, however, maincontroller 20 moves predetermined blades of the movable reticle blind(not shown) within illumination system 10 synchronously with reticlestage RST, which prevents exposure from being performed on unnecessaryareas of wafer W1 before the scanning exposure has been started.

Then, different areas in the pattern area of reticle R are sequentiallyilluminated by illumination light IL, and when the entire pattern areahas been illuminated, scanning exposure of the first shot area of waferW1 is completed. By this operation, the pattern of reticle R is reducedand transferred onto the first shot area of wafer W1 via projectionoptical system PL.

In this case, after the exposure has been completed, main controller 20continues to move the movable reticle blind (not shown) withinillumination system 10 synchronously with reticle stage RST, whichprevents unnecessary exposure of wafer W1.

When the scanning exposure of the first shot area has been completed inthe manner described above, main controller 20 steps wafer stage WST1via X-axis linear motors 84 and 85 and Y-axis linear motor 81 in theX-axis and Y-axis directions, and wafer stage WST1 is moved to theacceleration starting position (scanning starting position) for exposingthe second shot area. During this stepping operation between shots, maincontroller 20 measures the positional displacement in the X, Y, and θzdirections real-time based on the measurement values of interferometers18 and 46. Then, based on the measurement results, main controller 20controls the position of wafer stage WST1 so that the XY positionaldisplacement of wafer stage WST1 moves into a predetermined state.Further, based on the displacement information of wafer stage WST1 inthe θz direction, main controller 20 controls the rotation of at leasteither the reticle stage RST (reticle fine movement stage) or waferstage WST1 so as to compensate the rotational displacement error on thewafer side.

Then, when the stepping operation between shots has been completed, maincontroller 20 controls the operation of each section as in thedescription above, and scanning exposure as in the description above isperformed on the second shot area of wafer W1.

In this manner, the scanning exposure of the shot area of wafer W1 andthe stepping operation for exposing the next shot are repeatedlyperformed, and the circuit pattern of reticle R is sequentiallytransferred onto all the shot areas subject to exposure on wafer W1.

Incidentally, during the exposure operation by the step-and-scan methodto wafer W1 described above, it is a matter of course that maincontroller 20 performs the open/close operation of each valve in liquidsupply unit 5 and liquid recovery unit 6 of liquid supply/drainagesystem 32 according to the moving direction of wafer W1 in a similarmanner as is previously described. Accordingly, during the exposureoperation by the step-and-scan method to wafer W1 described above, thestate where a constant amount of water is held stably in the spacebetween tip lens 91 and wafer W1 is maintained.

Next, details on a parallel processing operation using the two waferstages WST1 and WST2 will be described, referring to FIG. 2 and to FIGS.6 to 9. During the operation below, main controller 20 performs theopen/close operation of each valve in liquid supply unit 5 and liquidrecovery unit 6 of liquid supply/drainage system 32 according to themoving direction of the wafer stages positioned at the first areadirectly under projection unit PU as is previously described, and thespace directly under tip lens 91 of projection optical system PL isconstantly filled with the water. However, in the description below, forthe sake of simplicity, the description related to the control of liquidsupply unit 5 and liquid recovery unit 6 will be omitted.

FIG. 2 shows a state where exposure of wafer W1 on wafer stage WST1 isperformed by the step-and-scan method in the manner previouslydescribed, while on the wafer stage WST2 side, wafer alignment of waferW2 positioned at the third area under alignment system ALG2 is beingperformed in parallel with the exposure.

While exposure of wafer W1 is performed by the step-and-scan method inthe manner described above, the following operation is being performedon the wafer stage WST2 side.

More specifically, prior to the wafer alignment referred to above, at aleft-hand side loading position, wafer exchange is performed between awafer carrier mechanism (not shown) and wafer stage WST2. In this case,the left-hand side loading position is to be determined at a positiondirectly under alignment system ALG2 where fiducial mark plate FM2 ispositioned. In this case, at the left-hand side loading position, maincontroller 20 resets Y-axis interferometer 44 before alignment systemALG2 detects the second fiducial marks formed on fiducial mark plateFM2.

On the detection of the second fiducial marks referred to above, maincontroller 20 picks up the images of the second fiducial marks usingalignment system ALG2, and performs a predetermined processing on theimaging signals, and by analyzing the signals that have been processed,main controller 20 detects the position of the second fiducial markswith the index center of alignment system ALG2 serving as a reference.Further, based on the detection results of the position of the secondfiducial marks and the measurement results of interferometers 16 and 44on the detection, main controller 20 computes the position coordinatesof the second fiducial marks on the second alignment coordinate system.

Next, by detecting positional information (positional information withrespect to the detection center of alignment system ALG2) of alignmentmarks (sample marks) arranged in a specific plurality of shot areas(sample shot areas) on wafer W2 using alignment system ALG2 whilecontrolling the position of wafer stage WST2 on the second alignmentcoordinate system referred to earlier, main controller 20 obtains thepositional information of the sample marks on the second alignmentcoordinate system. Then, based on the detection results and the designposition coordinates of the specific shot areas, main controller 20executes statistical calculation such as the one disclosed in, forexample, Kokai (Japanese Patent Unexamined Application Publication) No.61-22249 and the corresponding U.S. Pat. No. 4,780,617, and computes orcalculates the position coordinates of the plurality of shot areas onwafer W2 on the second alignment coordinate system. That is, in themanner described above, EGA (Enhanced Global Alignment) is performed.And then, by subtracting the position coordinates of the second fiducialmarks described above from the position coordinates of the plurality ofshot areas on wafer W2 on the second alignment coordinate system, maincontroller 20 converts the position coordinates of the plurality of shotareas into position coordinates using the position of the secondfiducial marks as its origin. As long as the national laws in designatedstates or elected states, to which this international application isapplied, permit, the above disclosures of the Kokai publication and theU.S. patent are incorporated herein by reference.

Normally, in the exposure sequence and the wafer alignment/exchangesequence performed in parallel on the two stages, wafer stages WST1 andWST2, the wafer alignment/exchange sequence is completed before theexposure sequence. Therefore, wafer stage WST2 on which alignment hasbeen completed moves into a waiting state at a predetermined waitingposition.

Then, at the point where exposure of wafer W1 has been completed on thewafer stage WST1 side, main controller 20 begins to move wafer stagesWST1 and WST2 toward a predetermined position shown in FIG. 6.

Then, after wafer stages WST1 and WST2 are moved to the position shownin FIG. 6, main controller 20 begins an operation of simultaneouslydriving wafer stages WST1 and WST2 in the +X direction. In the stateshown in FIG. 6, wafer stage WST1 and wafer stage WST2 are in contactvia elastic seal member 93 applied to wafer stage WST1.

When main controller 20 simultaneously drives wafer stages WST1 and WST2in the manner described above, in the state shown in FIG. 6, the waterheld in the space between tip lens 91 of projection unit PU and wafer W1sequentially moves over the following areas along with the movement ofwafer stages WST1 and WST2 to the +X side: wafer W1→wafer stage WST1(wafer holder H1, to be more specific)→wafer stage WST2 (wafer holderH2, to be more specific). During the movement, wafer stages WST1 andWST2 maintain the positional relation of being in contact via elasticseal member 93 as in the state shown in FIG. 6. FIG. 7 shows a statewhere the water (the immersion area) simultaneously exists on both waferstages WST1 and WST2 (wafer holders H1 and H2) during the movementabove, that is, the state just before the water is passed over fromwafer stage WST1 to wafer stage WST2.

When wafer stages WST1 and WST2 are further driven simultaneously by apredetermined distance in the +X direction from the state shown in FIG.7, then the water moves into a state where it is held in the spacebetween the area including fiducial mark plate FM2 on wafer stage WST2and tip lens 91 as is shown in FIG. 8. And, prior to this state, maincontroller 20 resets Y-axis interferometer 46 at some point where theinterferometer beam from Y-axis interferometer begins to be irradiatedon movable mirror 117Y.

Next, main controller 20 begins to drive wafer stage WST1 toward aright-hand side loading position shown in FIG. 9. The right-hand sideloading position is to be determined at a position directly underalignment system ALG1 where fiducial mark plate FM1 is positioned.

In parallel with starting to move wafer stage WST1 toward the right-handside loading position, main controller 20 detects the relative positionbetween the first fiducial marks in pairs on fiducial mark plate FM2 andthe projected images on the wafer surface of the reticle alignment markson reticle R corresponding to the first fiducial marks with reticlealignment system RAa and RAb (refer to FIG. 1) in pairs, usingillumination light IL. On this detection, the first fiducial marks inpairs on fiducial mark plate FM2 and the images of the reticle alignmentmarks are detected via projection optical system PL and the water.

Then, based on the relative position information that has been detected,the positional information of each shot area on wafer W2 with respect tothe second fiducial marks obtained in advance, and the known positionalrelation between the first fiducial mark and the second fiducial mark,main controller 20 computes the relative positional relation between theprojection position (the projection center of projection optical systemPL) of the pattern of reticle R and each shot area on wafer W2. And,based on the computation results, main controller 20 transfers thepattern of reticle R on each shot area of wafer W2 by the step-and-scanmethod while controlling the position of wafer stage WST2 on the secondexposure coordinate system as in the case of wafer W1 described above.

In parallel with the operation on the wafer stage WST2 side describedabove, on the wafer stage WST1 side at the right-hand side loadingposition, wafer exchange is performed with a wafer carrier system (notshown), and at the same time, or immediately after the wafer exchange,main controller 20 performs detection of the second fiducial marks onfiducial mark plate FM1 using alignment system ALG1. Prior to thedetection of the second fiducial marks, main controller 20 resets Y-axisinterferometer 48. Then, main controller 20 performs EGA on W2 usingalignment system ALG1 while controlling the position of wafer stage WST1on the first alignment coordinate system.

Hereinafter, main controller repeats the parallel operation performed onwafer stages WST1 and WST2 described above.

On the parallel processing using wafer stage WST1 and wafer stage WST2,during the period while the exposure of the wafer on one of the waferstages is completed until the exposure of the wafer on the other waferstage is started, transition from a state where one of the wafer stagesis directly under projection unit PU (that is, a state where the wateris located on one of the wafer stages) to a state where the other waferstage is directly under projection unit PU (that is, a state where thewater is located on the other wafer stage) is performed. During thistransition, the state where wafer stage WST1 and wafer stage WST2 are incontact in the X-axis direction via elastic seal member 93 (the stateshown in FIG. 10) is maintained as is previously described. Therefore,even if a state where the water (the immersion area) crosses both waferstages WST1 and WST2 occurs as is shown in FIG. 7, elastic seal member93 prevents the water (liquid) from leaking under the stage via the gapbetween wafer stages WST1 and WST2 without fail.

While wafer stage WST1 and wafer stage WST2 are being moved, a state(moving period, moving interval) occurs where the interferometer beamsfrom both Y-axis interferometers 46 and 48 do not irradiate movablemirror 17Y of wafer stage WST1, and a state (moving period, movinginterval) also occurs where the interferometer beams from both Y-axisinterferometers 46 and 44 do not irradiate movable mirror 117Y of waferstage WST2. In the embodiment, however, a linear encoder (not shown)controls the position of both of the stages WST1 and WST2 in such astate. In the case the linear encoder controls the position of the waferstages, main controller 20 resets the Y-axis interferometer at the pointwhere the interferometer beam from either of the Y-axis interferometersbegins to irradiate movable mirrors 17Y or 117Y.

As is obvious from the description so far, in the embodiment, waferstage drive section 124 configures at least apart of a stage drivesystem. Further, the stage drive system, wafer stage WST1, and waferstage ST2 configures at least a part of a stage unit.

As is described above in detail, according to exposure apparatus 100,the stage unit equipped in the exposure apparatus, and the drive methodof wafer stages WST1 and WST2 executed in exposure apparatus 100 of theembodiment, when a transition is performed from a first state where oneof the wafer stages WST1 (or WST2) is positioned at a first areaincluding the position directly under projection unit PU to which theliquid (water) is supplied to a second state where the other wafer stageWST2 (or WST1) is positioned at the first area, the stage drive system(such as 124) simultaneously drives wafer stages WST1 and WST2 in theX-axis direction while maintaining the state where wafer stage WST1 andwafer stage WST2 are in contact in the X-axis direction via elastic sealmember 93.

Therefore, it becomes possible to perform the transition from the firststate where one of the wafer stages WST1 (or WST2) is positioned at thefirst area to a second state where the other wafer stage WST2 (or WST1)is positioned at the first area in a state where the water continues tobe supplied to the space between projection optical system PL(projection unit PU) and the specific wafer stage (this stage switchesfrom one of the wafer stages to the other wafer stage with the movement)directly below projection optical system PL without leaking any waterfrom the gap between the wafer stages. More specifically, the transitionfrom a state where the water is held in the space between one of thewafer stages and projection optical system PL to a state where the wateris held in the space between the other wafer stage and projectionoptical system PL can be performed during the period after the exposureoperation of the wafer on one of the wafer stages via projection opticalsystem PL and the water (liquid) has been completed until the exposureof the wafer on the other wafer stage via projection optical system PLand the water (liquid) is started, without going through the process offully recovering the water and then supplying the water again.

Accordingly, it becomes possible to improve the throughput by reducingthe time (that is, to maintain the time around the same level as atypical exposure apparatus (a non-immersion type exposure apparatus)that does not perform immersion exposure) from after the completion ofthe exposure operation on one of the wafer stages until the beginning ofthe exposure operation on the other wafer stage. Further, because thewater constantly exists on the image plane side of projection opticalsystem PL, generation of water stains (water marks) on the opticalmembers (e.g. tip lens 92, the prisms of the multiple point focalposition detection system previously described, or the like) on theimage plane side of projection optical system PL can be effectivelyprevented, which allows the image-forming performance of projectionoptical system PL and the detection accuracy of the multiple point focalposition detection system to be favorably maintained for over a longperiod of time.

Further, the parallel processing operation of wafer stages WST1 and WST2can improve the throughput of the exposure apparatus improved whencompared with a conventional exposure apparatus that has a single waferstage and sequentially performs wafer exchange, wafer alignment, andexposure operations using the single wafer stage.

Further, by performing exposure with high resolution and a larger depthof focus than in the air by the immersion exposure, the pattern ofreticle R can be transferred with good precision on the wafer, and forexample, transfer of a fine pattern that has a device rule of around 70to 100 nm can be achieved.

Further, in the embodiment, because wafer stage WST1 and wafer stageWST2 are in contact via elastic seal member 93, water leakage from thegap between both stages can be suppressed, and in addition, the dampereffect of elastic seal member 93 can reduce the impact when wafer stageWST1 and wafer stage WST2 comes into contact.

Furthermore, in the embodiment, because there are no movable mirrors forthe interferometers on the −X side surface of wafer stage WST1 and the+X side surface of wafer stage WST2, the reflection surfaces of themovable mirrors on both wafer stages do not face each other closelytogether even when both stages are close together in the X-axisdirection. This allows not only the position of both stages to bemonitored by interferometer system 118 while both wafer stages aredriven simultaneously in the X-axis direction, but also prevents thewater from adhering to the reflection surface.

A Second Embodiment

Next, a second embodiment of the present invention will be described,referring to FIGS. 11 to 15B. For parts that have the same or similararrangement as the first embodiment previously described, the samereference numerals will be used, and the description thereabout will bebrief, or entirely omitted. In the exposure apparatus of the secondembodiment, the configuration or the like of the wafer stage unit andthe parallel processing operation using the two wafer stages differ fromthe first embodiment previously described. Further, the point where onlyone mark detection system is arranged is also different from the firstembodiment previously described. The configuration or the like of othercomponents or assemblies are similar to the first embodiment previouslydescribed. Accordingly, from the viewpoint of avoiding repetition in thefollowing description, the differences will mainly be described.

FIG. 11 shows an arrangement of a control system in the exposureapparatus of the second embodiment. When FIG. 11 is compared to FIG. 5,it can be seen that in the second embodiment, instead of wafer stagedrive section 124 in the first embodiment previously described, thepoint where a wafer stage drive section 124A is arranged is differentfrom the first embodiment previously described.

In the second embodiment, instead of wafer stage unit 50 describedearlier, a wafer stage unit 50′ shown in FIG. 12 is arranged. As isshown in FIG. 12, wafer stage unit 50′ is equipped with a base platform12, wafer stage WST1′ and wafer stage WST2′ arranged above (the frontside of the page surface of FIG. 12) the upper surface of base platform12, six interferometers 151X₁, 151X₂, 151X₃, 151X₄, 151Y₁, and 151Y₂ formeasuring the positions of wafer stages WST1′ and WST2′, a first drivesection 171 and a second drive section 172 shaped roughly in a letter Hin a planar view (when viewed from above) that individually drive waferstages WST1′ and WST2′, and a first connecting mechanism 195 and asecond connecting mechanism 196 (not shown in FIG. 12, refer to FIG.11).

In this case, the six interferometers 151X₁, 151X₂, 151X₃, 151X₄, 151Y₁,and 151Y₂ referred to above constitute an interferometer system 118Ashown in FIG. 11, and wafer stage drive section 124A shown in FIG. 11 isconfigured including the first drive section 171, the second drivesection 172, the first connecting mechanism 195, and the secondconnecting mechanism 196.

The first drive section 171 is equipped with an X-axis linear motor 136Xserving as a linear actuator for driving wafer stage WST1′ (or WST2′) inthe X-axis direction, and Y-axis linear motors 136Y₁, and 136Y₂ in pairsthat integrally drive wafer stage WST1′ (or WST2′) in the Y-axisdirection, which is the scanning direction, with X-axis linear motor136X.

X-axis linear motor 136X is equipped with an X-axis linear guide 181serving as a stator whose longitudinal direction is the X-axisdirection, and an X mover 179 that moves in the X-axis direction alongX-axis linear guide 181.

X-axis linear guide 181 is composed of a housing that extends in theX-axis direction, and an armature unit that has a plurality of armaturecoils arranged along the X-axis direction at a predetermined distanceinside the housing. On one end of X-axis linear guide 181 in thelongitudinal direction (the X-axis direction), a mover (Y mover) 184 ofone of the Y-axis linear motors, 136Y₁, is fixed, and on the other end,a mover (Y mover) 185 of the other Y-axis linear motor, 136Y₂, is fixed.

X mover 179, for example, has a cylindrical shape that surrounds X-axislinear guide 181 from all around, and inside X mover 179 a mover yokewhose YZ sectional surface is a reversed U-shape is arranged. In themover yoke, a plurality of N-pole permanent magnets and S-pole permanentmagnets are arranged alternately along the longitudinal direction.Therefore, in the space inside X mover 179, an alternating magneticfield is formed along the X-axis direction.

In this case, by the electromagnetic interaction between X-mover 179 andX-axis linear guide 181, a drive force (Lorentz force) that drives Xmover 179 in the X-axis direction is generated. That is, X-axis linearmotor 136X is a moving magnet type linear motor by the electromagneticdrive method.

On the −Y side surface of X mover 179, the first connecting mechanism195 (not shown in FIG. 12, refer to FIG. 11) for connecting wafer stageWST1′ (or WST2′) is arranged. As the first connecting mechanism 195, forexample, a mechanism that uses the electromagnetic suction of anelectromagnet or a mechanism that mechanically engages wafer stage WST1′(or WST2′) can also be used. Main controller 20 controls the firstconnecting mechanism 195 so as to connect X mover 179 to wafer stageWST1′ (or WST2′) or to release the connection. Incidentally, in aconnected state, wafer stage WST1′ (or WST2′) is in a state where it iscantilevered by X mover 179. FIG. 12 shows the state where X mover 179cantilevers wafer stage WST1′ (or WST2′).

One of the Y-axis linear motors 136Y₁ is equipped with a Y-axis linearguide 188 serving as a stator arranged extending in the Y-axisdirection, and a Y mover 184 that moves along Y-axis linear guide 188.As Y-axis linear guide 188, an armature unit having a similararrangement as X-axis linear guide 181 previously described is used.Further, as Y mover 184, a magnetic pole unit having a similararrangement as X mover 179 previously described but with a reversedU-shape in the XZ section is used. That is, Y-axis linear motor 136Y₁ isa moving magnet type linear motor by the electromagnetic drive method.

The other Y-axis linear motor 136Y₂ is equipped with a Y-axis linearguide 189 serving as a stator arranged extending in the Y-axisdirection, and a Y mover 185 that moves along Y-axis linear guide 189.Y-axis linear motor 136Y₂ is also a moving magnet type linear motor bythe electromagnetic drive method that is configured in a similar manneras Y-axis linear motor 136Y₁.

Further, because both ends of X-axis linear guide 181 are respectivelyfixed to movers 184 and 185 as is previously described, when Y-axislinear motors 136Y₁ and 136Y₂ generate a drive force in the Y-axisdirection, wafer stage WST1′ (or WST2′) is also driven in the Y-axisdirection with X-axis linear motor 136X. In this case, by making Y-axislinear motors 36Y₁ and 36Y₂ generate different drive forces, therotation around the Z-axis of wafer stage WST1′ (or WST2′) can becontrolled via X-axis liner motor 36X.

The second drive section 172 is arranged on the −Y side of the firstdrive section 171 described earlier, arranged substantially diphycercalwithin the page surface of FIG. 12. The second drive section 172 isconfigured in a similar manner as the first drive section 171 describedabove. More specifically, the second drive section 172 is equipped withan X-axis linear motor 138X serving as a linear actuator configured ofan X-axis linear guide 180 and an X mover 178, a Y-axis linear motor138Y₁ configured of a Y mover 182 arranged on one end of X-axis linearguide 180 and a Y-axis linear guide 186, and a Y-axis linear motor 138Y₂configured of a Y mover 183 arranged on the other end of X-axis linearguide 180 and a Y-axis linear guide 187.

Similar to X mover 179, on the +Y surface side of X mover 178, thesecond connecting mechanism 196 (not shown in FIG. 12, refer to FIG. 11)similar to the first connecting mechanism 195 for connecting wafer stageWST1′ (or WST2′) is arranged. Main controller 20 controls the secondconnecting mechanism 196 so as to connect X mover 178 to wafer stageWST2′ (or WST1′) or to release the connection. FIG. 12 shows the statewhere X mover 178 cantilevers wafer stage WST2′ (or WST2′).

Wafer stage WST1′ is configured of a stage main body without anymagnetic pole units arranged, which is different from the stage mainbody constituting wafer stage WST1 of the first embodiment previouslydescribed, and a wafer table similar to the wafer table constitutingwafer stage WST1 previously described arranged on the upper surface ofthe stage main body via a Z-tilt drive mechanism (not shown). On theupper surface of the wafer table, a +Y movable mirror 47Y₁, −Y movablemirror 47Y₂, and a +X movable mirror 47X are arranged in the vicinity ofthe edge section on the ±Y side and the +X side.

Wafer stage WST2′ has an arrangement similar to wafer stage WST1′referred to above. On the upper surface of the wafer table constitutingwafer stage WST2′, a +Y movable mirror 49Y₁, −Y movable mirror 49Y₂, anda −X movable mirror 49X are arranged in the vicinity of the edge sectionon the ±Y side and the −X side.

In the second embodiment as well, an elastic seal member similar toelastic seal member 93 shown in FIG. 10 is arranged on at least eitherthe side surface of wafer stage WST1′ on which the movable mirror is notarranged (the −X side surface) or the side surface of wafer stage WST2′on which the movable mirror is not arranged (the +X side surface).

Further, as is shown in FIG. 12, an alignment system ALG is arranged onthe −Y side of projection optical system PL a predetermined distanceaway.

As is shown in FIG. 12, interferometer system 118A has two Y-axisinterferometers 151Y₁ and 151Y₂ whose measurement axes are parallel tothe Y-axis. The measurement axes respectively pass through theprojection center of projection optical system PL (optical axis AX) andthe detection center of alignment system ALG. Interferometer system 118Aalso has two X-axis interferometers 151X₁ and 151X₂ whose measurementaxes are parallel to the X-axis. The measurement axes also respectivelycross the measurement axis of interferometer 151Y₁ perpendicularly atthe projection center of projection optical system PL (optical axis AX).Interferometer system 118A also has two more X-axis interferometers151X₃ and 151X₄ whose measurement axes are parallel to the X-axis. Themeasurement axes also respectively cross the measurement axis ofinterferometer 151Y₂ perpendicularly at the detection center ofalignment system ALG.

The four X-axis interferometers 151X₁ to 151X₄ are multi-axisinterferometers that have at least three measurement axes that areseparate in the Y-axis direction and the Z-axis direction, and theoutput values of each optical axis can be measured independently.Accordingly, with the four X-axis interferometers 151X₁ to 151X₄, otherthan measuring the position of wafer stages WST1′ and WST2′ in theX-axis direction, the rotation amount around the Y-axis (rolling amount)and the rotation amount around the Z-axis (yawing amount) can also bemeasured.

The two Y-axis interferometers 151Y₁ and 151Y₂ are dual-axisinterferometers each having two optical axes that are separate, forexample, in the Z-axis direction, and the output values of each opticalaxis can be measured independently. Accordingly, with the Y-axisinterferometers 151Y₁ and 151Y₂, other than measuring the position ofwafer stages WST1′ and WST2′ in the Y-axis direction, the rotationamount around the X-axis (pitching amount) can also be measured.

In this case, when wafer stage WST1′ is in the area (a first area) inthe vicinity of the position directly under the optical axis ofprojection optical system PL and exposure of the wafer on wafer stageWST1′ (wafer W1 in FIG. 12) is to be performed, the position of waferstage WST1′ within the XY plane is controlled on a first exposurecoordinate system, which is set by the measurement axes of X-axisinterferometer 151X₁ and Y-axis interferometer 151Y₁.

Further, when wafer stage WST2′ is in the first area of projectionoptical system PL and exposure of the wafer on wafer stage WST2′ (waferW2 in FIG. 12) is to be performed, the position of wafer stage WST2′within the XY plane is controlled on a second coordinate system, whichis set by the measurement axes of X-axis interferometer 151X₂ and Y-axisinterferometer 151Y₁.

Further, when wafer stage WST1′ is in the area (a second area) in thevicinity of the position directly under the detection center ofalignment system ALG, and in the case such as when alignment (EGA) ofthe wafer on wafer stage WST1′ (wafer W1 in FIG. 12) is to be performed,the position of wafer stage WST1′ within the XY plane is controlled on afirst alignment coordinate system, which is set by the measurement axesof X-axis interferometer 151X₃ and Y-axis interferometer 151Y₂.

Furthermore, when wafer stage WST2′ is in the area (a second area) inthe vicinity of the position directly under the detection center ofalignment system ALG, and in the case such as when alignment (EGA) ofthe wafer on wafer stage WST2′ (wafer W2 in FIG. 12) is to be performed,the position of wafer stage WST2′ within the XY plane is controlled on asecond alignment coordinate system, which is set by the measurement axesof X-axis interferometer 151X₄ and Y-axis interferometer 151Y₂

The other sections in the configuration including liquid supply/drainagesystem 32 are configured in the same manner as in the first embodimentpreviously described.

Next, a series of operations including a parallel processing operationsuch as an exposure operation of a wafer on one of the wafer stages andan alignment operation of a wafer on the other wafer stage will bedescribed, referring to FIGS. 12 to 15B. During the operation below,main controller 20 performs the open/close operation of each valve inliquid supply unit 5 and liquid recovery unit 6 of liquidsupply/drainage system 32 according to the moving direction of the waferstages positioned at the first area directly under projection unit PU asis previously described, and the space directly under a tip lens 91 ofprojection optical system PL is constantly filled with the water.However, in the description below, for the sake of simplicity, thedescription related to the control of liquid supply unit 5 and liquidrecovery unit 6 will be omitted.

While wafer stage WST1′ and wafer stage WST2′ are being moved, aninterval exists where the interferometer beams from the X-axisinterferometer or the Y-axis interferometer does not irradiate themovable mirrors and position control of the wafer stages by theinterferometers becomes difficult. In such a case, the position of thewafer stages is controlled by a linear encoder (not shown), and in thecase the linear encoder controls the position of the wafer stages, maincontroller 20 resets the desired interferometer at the point where theinterferometer beam from the desired interferometer begins to irradiatethe movable mirrors. However, in the description below, in order toavoid complication, the description related to measuring the position ofthe wafer stages by the linear encoder and the reset of theinterferometers will be omitted.

FIG. 12 shows a state where exposure of wafer W1 mounted on wafer stageWST1′ is performed in the manner similar to the first embodimentdescribed earlier by the step-and-scan method, while in parallel withthis operation on the wafer stage WST2′ side, wafer alignment of waferW2 is performed at the second area below alignment system ALG.

Main controller 20 performs the exposure operation of wafer W1 whilemoving wafer stage WST1′ by controlling the drive of X-axis linear motor136, and Y-axis linear motors 136Y₁ and 136Y₂ in pairs, whilecontrolling the position of wafer stage WST1′ on the first exposurecoordinate system.

While exposure is being performed on wafer W1 by the step-and-scanmethod on the wafer stage WST1′ side, the following operation isperformed on the wafer stage WST2′ side.

More specifically, prior to the wafer alignment described above, at apredetermined loading position, wafer exchange is performed between awafer carrier mechanism (not shown) and wafer stage WST2′.

After wafer exchange, main controller 20 executes the EGA previouslydescribed which includes detection the positional information of thesample marks arranged in the specific plurality of sample shot areas onwafer W2 using alignment system ALG while controlling the position ofwafer stage WST2′ on the second alignment coordinate system referred toearlier, and computes the position coordinates of a plurality of shotareas on wafer W2 on the second alignment coordinate system. FIG. 12shows a state during detection of the positional information of thesample marks. Further, around the time of detection of the positionalinformation of the sample marks, main controller 20 detects thepositional information of the second fiducial marks formed on a fiducialmark plate FM2 on wafer stage WST2′. Then, main controller 20 convertsthe position coordinates of the plurality of shot areas on wafer W2obtained in advance into position coordinates using the position of thesecond fiducial marks as its origin.

The movement of wafer stage WST2′ on the wafer alignment or the likedescribed above is performed by main controller 20, by driving andcontrolling X-axis linear motor 138X, and Y-axis linear motors 138Y₁ and138Y₂ in pairs previously described.

Normally, in the wafer alignment operation of wafer W2 on wafer stageWST2′ and the exposure operation of wafer W1 on wafer stage WST1′, thewafer alignment operation is completed before the exposure operation.Therefore, after the wafer alignment has been completed, main controller20 moves wafer stage WST2′ to a predetermined waiting position shown inFIG. 13A via X-axis linear motor 138X, and Y-axis linear motors 138Y₁and 138Y₂ in pairs, and makes wafer stage WST2′ wait at the position.

Then, when the exposure operation of wafer W on wafer stage WST1′ iscompleted, main controller 20 moves wafer stage WST1′ to the positionshown in FIG. 13A via X-axis linear motor 136, and Y-axis linear motors136Y₁ and 136Y₂ in pairs. The exposure completion position of wafer W1is preferably set in the vicinity of the position shown in FIG. 13A.

After moving wafer stage WST1′ to the position shown in FIG. 13A, maincontroller 20 moves wafer stage WST2′ via X-axis linear motor 138, andY-axis linear motors 138Y₁ and 138Y₂ in pairs to a position shown inFIG. 13B. In the state where wafer stage WST2′ has moved to the positionshown in FIG. 13B, wafer stage WST1′ and wafer stage WST2′ are incontact via the elastic seal member as in the first embodimentpreviously described.

Next, main controller 20 simultaneously moves wafer stage WST1′ andwafer stage WST2′ in the +X direction by controlling X-axis linear motor136, and Y-axis linear motors 136Y₁ and 136Y₂ in pairs, and X-axislinear motor 138, and Y-axis linear motors 138Y₁ and 138Y₂ in pairs.FIG. 14A shows a state where both wafer stages WST1′ and WST2′ have beenmoved simultaneously in the +X direction from the state shown in FIG.13B and the water is held in the space between the area includingfiducial mark plate FM2 on wafer stage WST2′ and tip lens 91.

In the state shown in FIG. 13B, the water that has been held or retainedin the space between tip lens 91 of projection unit PU and wafer W1sequentially moves over the following areas along with the movement ofwafer stages WST1′ and WST2′ to the +X side: wafer W1→wafer stageWST1′→wafer stage WST2′. During the movement, wafer stages WST1′ andWST2′ maintain the positional relation of being in contact via elasticseal member 93.

Next, main controller 20 releases the connected state of X mover 179 andwafer stage WST1′ by the first connecting mechanism 195 and theconnected state of X mover 178 and wafer stage WST2′ by the secondconnecting mechanism 196, and after this operation, main controller 20slightly moves X mover 179 in the +Y direction and X mover 178 in the −Ydirection. FIG. 14B shows the state after the X movers 179 and 178 havebeen driven or moved.

In the state shown in FIG. 14B, wafer stages WST1′ and WST2′ aresupported by levitation above base platform 12 by air pads (not shown)arranged on each of the bottom surfaces (the surface on the −Z side) ofwafer stages WST1′ and WST2′. However, without limitation to thisconfiguration, support legs that can freely appear can be arranged onthe wafer stages WST1′ and WST2′ side or on the base platform 12 side,and wafer stages WST1′ and WST2′ can be stably supported above baseplatform 12 by the legs just before the connections between wafer stageWST1′ and X mover 179 and wafer stage WST2′ and X mover 178 arereleased.

Next, main controller 20 drives X mover 179 via Y-axis linear motors136Y₁ and 136Y₂ in pairs and X-axis linear motor 136, and moves X mover179 to a position where it can be connected to wafer stage WST2′, andalso drives X mover 178 via Y-axis linear motors 138Y₁ and 138Y₂ inpairs and X-axis linear motor 138, and moves X mover 178 to a positionwhere it can be connected to wafer stage WST1′. At this point, theencoder (not shown) controls the position of each X mover.

FIG. 15A shows the state where X mover 179 is driven and moved to aposition where it can be connected to wafer stage WST2′, while X mover178 is driven and moved to a position where it can be connected to waferstage WST1′ in the manner described above. Then, main controller 20connects X mover 179 to wafer stage WST2′ via the first connectingmechanism 195, and also connects X mover 178 to wafer stage WST1′ viathe second connecting mechanism 196. The movement of X movers 178 and179 in the X direction and the attach/release of wafer stages WST1 andWST2 can be performed without any movement in the Y-axis direction.

After wafer stage WST2′ is connected to X mover 179 and wafer stageWST1′ is connected to X mover 178 in the manner described above, maincontroller 20 measures the first fiducial mark in pairs on fiducial markplate FM2 and the reticle alignment marks in pairs on reticle R, usingreticle alignment systems RAa and RAb, while controlling the position ofwafer stage WST2′ on the second exposure coordinate system previouslydescribed. Then, based on the measurement results and the results of thealignment performed earlier, main controller 20 moves wafer stage WST2′to the acceleration starting position for exposing the first shot areaon wafer W2. Then, main controller 20 drives and controls wafer stageWST2′ via X-axis linear motor 136, and Y-axis linear motors 136Y₁ and136Y₂ in pairs while controlling the position of wafer stage WST2′ onthe second exposure coordinate system, and the exposure operation ofwafer W2 is performed by the step-and-scan method in a similar manner asin the first embodiment previously described.

Meanwhile, main controller 20 moves wafer stage WST1′ toward a loadingposition via Y-axis linear motors 138Y₁ and 138Y₂, and X-axis linearmotor 136. The position of wafer stage WST1′ during this movement iscontrolled on the first alignment coordinate system. And, at the loadingposition, after wafer exchange of wafer W1 on wafer stage WST1′ that hasbeen exposed and the next wafer subject to exposure has been performed,main controller 20 performs the wafer alignment operation on the newwafer in a similar manner as the description above.

Then, at the point where wafer alignment of wafer stage WST1′ has beencompleted and the exposure operation on wafer stage WST2′ has beencompleted, wafer stage WST1′ and wafer stage WST2′ follow the pathsdescribed above completely backwards, and return to the state shown inFIG. 12.

As is described above, in the exposure apparatus of the secondembodiment, the exposure operation of a wafer on one stage and the waferexchange and wafer alignment operation on the other stage is performedin a simultaneous parallel processing, while performing a switchingoperation (switching) between wafer stages WST1′ and WST2′.

As is obvious from the description so far, in the second embodiment, astage drive system is configured including wafer stage drive section124A and main controller 20. Further, a stage unit is configuredincluding the stage drive system and wafer stages WST1′ and WST2′.Further, a switching unit is configured including the first connectingmechanism 195, the second connecting mechanism 196, Y-axis linear motors136Y₁ to 136Y₄, X-axis linear motors 136X and 138X, and main controller20 for controlling the parts above.

As is described above in detail, according to the exposure apparatus,the stage unit equipped in the exposure apparatus, and the drive methodof wafer stages WST1′ and WST2′ executed by the exposure apparatus inthe second embodiment, During transition from the first state in whichone of the wafer stages WST1′ (or WST2′) is positioned at the first areadirectly under projection optical system PL where the liquid is suppliedto the second state in which the other stage WST2′ (or WST1′) ispositioned at the first area, the stage drive system (20, 124A)simultaneously drives wafer stages WST1′ and WST2′ in the X-axisdirection while maintaining the state of wafer stages WST1′ and WST2′being in contact in the X-axis direction (the direction that intersectsthe Y-axis direction in which the first area and the second area closeto the position directly under the alignment system ALG are lined) viaelastic seal member 93.

Therefore, it becomes possible to perform the transition from the firststate in which one of the wafer stages WST1′ (or WST2′) is positioned atthe first area to the second state in which the other stage WST2′ (orWST1′) is positioned at the first area, in a state where the water(liquid) is supplied (held) in the space between projection opticalsystem PL and the specific wafer stage directly below projection opticalsystem PL (this wafer stage switches from one of the wafer stages to theother wafer stages due to the movement of the stages), without leakingthe liquid from the gap between both stages. More specifically, thetransition from a state where the water is held in the space between oneof the wafer stages and projection optical system PL to a state wherethe water is held in the space between the other wafer stage andprojection optical system PL can be performed during the period afterthe exposure operation of the wafer on one of the wafer stages viaprojection optical system PL and the water (liquid) has been completeduntil the exposure of the wafer on the other wafer stage via projectionoptical system PL and the water (liquid) is started, without goingthrough the process of fully recovering the water and then supplying thewater again. Accordingly, it becomes possible to improve the throughputby reducing the time (that is, to maintain the time around the samelevel as a typical exposure apparatus (a non-immersion type exposureapparatus) that does not perform immersion exposure) from after thecompletion of the exposure operation on one of the wafer stages untilthe beginning of the exposure operation on the other wafer stage.Further, because the water constantly exists on the image plane side ofprojection optical system PL, for the same reasons as in the firstembodiment previously described, the image-forming performance ofprojection optical system PL and the detection accuracy of the multiplepoint focal position detection system can be favorably maintained forover a long period of time.

Further, the parallel processing operation of wafer stages WST1′ andWST2′ can improve the throughput of the exposure apparatus improved whencompared with a conventional exposure apparatus that has a single waferstage and sequentially performs wafer exchange, wafer alignment, andexposure operations using the single wafer stage.

Further, also in the exposure apparatus of the second embodiment, byperforming exposure with high resolution and a larger depth of focusthan in the air by the immersion exposure, the pattern of reticle R canbe transferred with good precision on the wafer.

Further, also in the second embodiment, for the same reasons as in thefirst embodiment previously described, water leakage from the gapbetween both stages can be suppressed, and in addition, the impact whenwafer stage WST1 and wafer stage WST2 comes into contact can be reduced.

Furthermore, also in the second embodiment, because there are no movablemirrors for the interferometers on the −X side surface of wafer stageWST1′ and the +X side surface of wafer stage WST2′ as in the firstembodiment previously described, the reflection surfaces of the movablemirrors on both wafer stages do not face each other closely togethereven when both stages are close together in the X-axis direction. Thisallows not only the position of both stages to be monitored byinterferometer system 118A while both wafer stages are drivensimultaneously in the X-axis direction, but also prevents the water fromadhering to the reflection surface.

In the second embodiment above, the case has been described where threemovable mirrors are arranged on both wafer stages WST1′ and WST2′ andsix interferometers are arranged, however, the arrangement of themovable mirrors and the interferometers is not limited to thearrangement described in the second embodiment above. For example, twomovable mirrors can be arranged on both of the stages, and anarrangement of the interferometers that allows the position of bothwafer stages to be measured using the respective mirrors can beemployed.

Further, in the second embodiment above, the shifting by X movers 178and 179 is performed after the water held under tip lens 91 moves fromabove one of the stages to the other stage. The shifting by X movers 178and 179, however, can be performed before the water moves from above oneof the stages to the other stage.

A Third Embodiment

Next, a third embodiment of the present invention will be described,referring to FIGS. 16 to 18B. For components or assemblies that have thesame or similar arrangement as the first embodiment previouslydescribed, the same reference numerals will be used, and the descriptionthereabout will be brief, or entirely omitted. In the exposure apparatusof the third embodiment, only the configuration or the like of the waferstage unit differ from the first embodiment previously described, andthe configuration or the like of other components are similar to thefirst embodiment previously described. Accordingly, from the viewpointof avoiding repetition in the following description, the differenceswill mainly be described.

Different from wafer stage unit 50 that constitutes the exposureapparatus of the first embodiment previously described, as is shown inFIG. 16, a wafer stage unit 50″ of the third embodiment is equipped witha wafer stage WST on which a wafer can be loaded, and a measurementstage MST used only for measurement.

Wafer stage WST and measurement stage MST correspond to wafer stage WST1and wafer stage WST2 described earlier in the first embodiment, and aredriven within a two-dimensional plane by a wafer stage drive section (80to 87) similar to the drive section in the first embodiment.

Further, in the vicinity of a projection optical system PL (the barrelof projection unit PU), only one alignment system ALG is arranged.Projection unit PU and alignment system ALG are actually arranged in anested state, as is shown in FIG. 16. More specifically, at least thelower end section of alignment system ALG is positioned on the outerside of the section in the vicinity of the lower end section ofprojection unit PU whose diameter is smaller than the other sections(the section surrounding the tip lens) on the section below the largediameter section of projection unit PU.

On the upper surface of measurement stage MST, various measurementmembers are arranged. As such measurement members, for example, afiducial mark plate on which a plurality of fiducial marks are formed ora sensor that receives illumination light IL via projection opticalsystem PL such as the ones disclosed in, for example, Kokai (JapaneseUnexamined Patent Application Publication) No. 5-21314, and thecorresponding U.S. Pat. No. 5,243,195 are included. As the sensor, anillumination monitor having a photodetection section of a predeterminedarea for receiving illumination light IL on the image plane ofprojection optical system PL whose details are disclosed in Kokai(Japanese Unexamined Patent Application Publication) No. 11-16816, andthe corresponding U.S. Patent Application Publication No. 2002/0061469,an uneven illuminance measuring sensor, which has a pinhole-shapedlight-receiving section that receives illumination light IL on the imageplane of projection optical system PL whose details are disclosed inKokai (Japanese Unexamined Patent Application Publication) No. 57-117238and the corresponding U.S. Pat. No. 4,465,368, or an aerial imagemeasuring instrument that measures the light intensity of the aerialimage (projected image) of the pattern projected by projection opticalsystem PL whose details are disclosed in Kokai (Japanese UnexaminedPatent Application Publication) No. 2002-14005, and the correspondingU.S. Patent Application Publication No. 2002/0041377 can be employed. Aslong as the national laws in designated states or elected states, towhich this international application is applied, permit, the abovedisclosures of the Kokai publications, the U.S. Patent applicationpublications, and the U.S. Patent are incorporated herein by reference.The measurement members installed on measurement stage MST is notlimited to the ones referred to above, and various measurement memberscan be installed when necessary.

In the embodiment, in response to the immersion exposure performed inwhich wafer W is exposed by exposure light (illumination light) IL viaprojection optical system PL and water, the illumination monitor, theirregular illuminance measuring sensor, and the aerial image measuringinstrument above used for measurement using illumination light IL are toreceive illumination light IL via projection optical system PL and thewater. Further, only a part of each sensor, such as the optical system,can be arranged on measurement stage MST, or the whole sensor can bedisposed on measurement stage MST.

Further, measurement members may or may not have to be installed onwafer stage WST.

Further, in the third embodiment, similar to the first embodimentpreviously described, an elastic seal member similar to elastic sealmember 93 in FIG. 10 is arranged on at least either the −X side surfaceof wafer stage WST or the +X side surface of measurement stage MST.

Hereinafter, details on a parallel processing operation using waferstage WST and measurement stage MST equipped in the exposure apparatusof the third embodiment will be described, referring to FIGS. 16 to 18B.In the exposure apparatus related to the third embodiment as well, aninterferometer system similar to the one used in the first embodiment isarranged, and the position of wafer stage WST and measurement stage MSTis controlled as in the first embodiment. In the description below, inorder to prevent redundant explanation, the description related tocontrolling the position of the stages by the interferometer system willbe omitted. And, in the operation below, as is previously described,main controller 20 performs the open/close operation of each valve inliquid supply unit 5 and liquid recovery unit 6 of liquidsupply/drainage system 32 according to the moving direction of the stagepositioned at the first area directly under projection unit PU, and thespace directly under tip lens 91 of projection optical system PL isconstantly filled with the water. However, in the description below, forthe sake of simplicity, the description related to the control of liquidsupply unit 5 and liquid recovery unit 6 will be omitted.

FIG. 16 shows a state where exposure by the step-and-scan method isperformed on wafer W in a manner similar to the first embodimentpreviously described. At this point, measurement stage MST is waiting ata predetermined waiting position where it does not bump into wafer stageWST.

Then, on the wafer stage WST side, for example, at the stage whereexposure of one lot (25 or 50 wafers in one lot) of wafer W iscompleted, main controller 20 moves measurement stage MST to theposition shown in FIG. 17A. In the state shown in FIG. 17A, measurementstage MST and wafer stage WST are in contact via the elastic sealmember.

Next, main controller 20 begins the operation of simultaneously drivingboth stages WST and MST in the +X direction, while maintaining thepositional relation between wafer stage WST and measurement stage MST inthe X-axis direction.

When main controller 20 simultaneously drives wafer stage WST andmeasurement stage MST in the manner described above, in the state shownin FIG. 17A, the water held in the space between tip lens 91 ofprojection unit PU and wafer W sequentially moves over the followingareas along with the movement of wafer stage WST and measurement stageMST to the +X side: wafer W→wafer stage WST→measurement stage MST.During the movement, wafer stage WST and measurement stage MST maintainthe positional relation of being in contact via the elastic seal memberas in the state shown in FIG. 17A. FIG. 17B shows a state where thewater (the immersion area) simultaneously exists on both wafer stage WSTand measurement stage MST during the movement above, that is, the statejust before the water is passed over from wafer stage WST to measurementstage MST.

When wafer stage WST and measurement stage MST are further drivensimultaneously by a predetermined distance in the +X direction from thestate shown in FIG. 17B, then it becomes a state where the water is heldin between measurement stage MST and tip lens 91 as is shown in FIG.18A.

Next, main controller 20 moves wafer stage WST to a predetermined waferexchange position and also exchanges the wafer, and in parallel withthis, executes a predetermined measurement using measurement stage MSTas necessary. As an example of this measurement, baseline measurement ofalignment system ALG performed after the reticle has been exchanged onreticle stage RST can be given. To be more specific, main controller 20detects a first fiducial mark in pairs on a fiducial mark plate FMarranged on measurement stage MST and the corresponding reticlealignment marks on the reticle at the same time using reticle alignmentsystems RAa and RAb previously described, and detects the positionalrelation between the first fiducial mark in pairs and the correspondingreticle alignment marks. And, at the same time, by also detecting secondfiducial marks on fiducial mark plate FM with the alignment system ALG,main controller 20 detects the positional relation between the detectioncenter of alignment system ALG and the second fiducial mark. Then, basedon the positional relation between the first fiducial mark in pairs andthe corresponding reticle alignment marks and the positional relationbetween the detection center of alignment system ALG and the secondfiducial marks obtained above, and the known positional relation betweenthe first fiducial mark in pairs and the second fiducial marks, maincontroller 20 obtains the distance between the projection center(projection position) of the reticle pattern by projection opticalsystem PL and the detection center (detection position) of alignmentsystem ALG, that is, obtains the baseline of alignment system ALG. FIG.18B shows this state.

Reticle alignment marks in a plurality of pairs have been formed on thereticle and also the first fiducial mark in a plurality of pairs havebeen formed on fiducial mark plate FM corresponding to the retilealignment marks, and along with measuring the baseline of alignmentsystem ALG described above, by measuring the relative position of atleast two pairs of the first fiducial marks and the correspondingreticle alignment marks using reticle alignment systems RAa and RAbwhile moving reticle stage RST and measurement stage MST, the so-calledreticle alignment is performed.

In this case, mark detection using reticle alignment systems RAa and RAbis performed via projection optical system PL and the water.

Then, at the point where the operations described above on both stagesWST and MST have been completed, main controller 20 moves measurementstage MST and wafer stage WST, for example, within the XY plane whilemaintaining the state in which measurement stage MST and wafer stage WSTare in contact via the elastic seal member, and then as is previouslydescribed, main controller 20 performs wafer alignment on wafer W thathas been exchanged, or in other words, performs detection of thealignment marks on wafer W that has been exchanged with alignment systemALG, and computes the position coordinates of a plurality of shot areason wafer W.

Then, opposite to the operation above, main controller 20 simultaneouslydrives wafer stage WST and measurement stage MST in the −X directionwhile maintaining the positional relation of both stages in the X-axisdirection, and then withdraws measurement stage MST to a predeterminedposition after wafer stage WST (wafer W) moves to the position underprojection optical system PL, that is, after the immersion area hasmoved from the surface of measurement stage MST to the surface of waferstage WST (or wafer W).

Then, main controller 20 performs the exposure operation by thestep-and-scan method on wafer W, and sequentially transfers the reticlepattern onto the plurality of shot areas on wafer W. Moving wafer stageWST to the acceleration starting position for exposing each shot area onwafer W is performed based on the position coordinates of the pluralityof shot areas on wafer W obtained by the wafer alignment above and onthe baseline measured just before moving wafer stage WST.

In the description above, as the measurement operation, the case hasbeen described where baseline measurement has been performed. Themeasurement, however, is not limited to this, and measurements such asilluminance measurement, irregular illuminance measurement, aerial imagemeasurement and the like can be performed using measurement stage MST,for example, in parallel with the wafer exchange, and the measurementresults can be reflected to the exposure of wafer W that will beperformed after the measurement. Further, the sensor installed onmeasurement stage MST is not limited to the ones described above, andfor example, a sensor that performs wavefront measurement can also bearranged.

Further, in the third embodiment described above, the case has beendescribed where wafer stage WST and measurement stage MST are movedwhile in contact when exposure of one lot of wafer W has been completed,and the water is held between projection optical system PL andmeasurement stage MST. However, it is a matter of course that theoperation above should be performed each time the wafer is exchanged soas to hold the water between projection optical system PL andmeasurement stage MST. Further, measurement of the baseline or the likecan be performed when exposure of one lot has been completed as ispreviously described, or the measurement can be performed each time thewafer is exchanged or after the exposure of a predetermined number ofwafers has been completed.

As is obvious from the description so far, in the third embodiment, awafer stage drive section (80 to 87) configures at least a part of astage drive system as in the first embodiment. Further, the stage drivessystem and wafer stage WST and measurement stage MST configures at leasta part of a stage unit.

As is described above, according to the exposure apparatus and the stageunit equipped in the exposure apparatus of the third embodiment, duringa transition is performed from a first state where wafer stage WST (ormeasurement stage MST) positioned at a first area directly underprojection unit PU to which the liquid (water) is supplied to a secondstate where measurement stage MST (or wafer stage WST) is positioned atthe first area, the stage drive system described above simultaneouslydrives wafer stage WST and measurement stage MST in the X-axis directionwhile maintaining the state where both stages are in contact in theX-axis direction via the elastic seal member. Therefore, it becomespossible to perform the transition from the first state where one of thestages is positioned at the first area to a second state where the otherstage is positioned at the first area in a state where the watercontinues to be supplied to the space between projection optical systemPL and the specific stage (this stage switches from one of the stages tothe other stage with the movement) directly below projection opticalsystem PL without leaking any water from the gap between both stages.More specifically, the transition from a state where the water is heldin the space between wafer stage WST and projection optical system PL toa state where the water is held in the space between measurement stageMST and projection optical system PL can be performed during the periodafter the exposure operation on the wafer stage WST side via projectionoptical system PL and the water (liquid) has been completed until themeasurement on the measurement stage MST side directly under projectionoptical system PL is started, without going through the process of fullyrecovering the water and then supplying the water again. Further, thesame applies to after the measurement with measurement stage MST hasbeen completed until the exposure by wafer stage WST begins.

Accordingly, it becomes possible to improve the throughput by reducing(that is, to maintain the time around the same level as a typicalexposure apparatus (a non-immersion type exposure apparatus) that doesnot perform immersion exposure) the time after the exposure operation onthe wafer stage WST side has been completed until the measurement on themeasurement stage MST side is started, and the time after themeasurement with measurement stage MST has been completed until theexposure by wafer stage WST begins. Further, because the water (liquid)constantly exists on the image plane side of projection optical systemPL, generation of water stains (water marks) previously described can beeffectively prevented.

Further, by performing exposure with high resolution and a larger depthof focus than in the air by the immersion exposure, the pattern ofreticle R can be transferred with good precision on the wafer, and forexample, transfer of a fine pattern that has a device rule of around 70to 100 nm can be achieved.

Further, because the various measurements can be performed using themeasurement members installed on measurement stage MST each time thewafer has been exchanged, and the measurement results can be reflectedon the exposure operation, the exposure of the wafer can be performedconstantly in a state adjusted with high precision.

In the case illumination light IL is not used in the measurementoperation performed using measurement stage MST, it is also possible toperform the measurement operation on the measurement stage side inparallel with the exposure operation on the wafer stage WST side.

Further, in the third embodiment above, wafer alignment is performed ina state where measurement stage MST and wafer stage WST are in contactvia the elastic seal member. However, wafer alignment can also beperformed by moving wafer stage WST under projection optical system PL(and alignment system ALG) in a state where the two stages are incontact before wafer alignment is performed, and then performing waferalignment after the withdrawal of measurement stage MST.

Further, in the third embodiment described above, the first fiducialmarks and the second fiducial marks on fiducial mark plate FM can bemeasured at the same time. However, after measuring one of the firstfiducial marks or the second fiducial marks, measurement stage MST canbe moved in a state where the water is held on measurement stage MST soas to measure the other mark.

As the elastic seal member used in the first to third embodimentsdescribed above, as is shown in FIG. 19A, an elastic seal member 93′ canbe used, which is attached in an embedded state to a groove 49 whosesectional shape is a rough trapezoid and is formed on the +X sidesurface of one of the stages (in this case, stage WST2 (WST2′, MST)).This arrangement also allows the same effect to be obtained as in eachof the embodiments above. The arrangement shown in FIG. 19A can beemployed not only in one of the stages but also in both stages.

Further, as is show in FIG. 19B, a groove 49′ whose sectional shape is arough trapezoid can be formed on the +X side surface of one of thestages (in this case, stage WST1 (WST1′, WST)) and an elastic sealmember 93″ can be attached in an embedded state to groove 49′, and aflat plate 94 can be arranged on the edge of the upper surface of theother stage (in this case, stage WST2 (WST2′, MST)) on the +X side. Inthis case, in a state where both stages are close together, the watercan be kept from leaking from between the stages by flat plate 94 cominginto contact with elastic seal member 93″, as is shown in FIG. 19B.

Further, as is shown in FIG. 19C, the entering and the leakage of thewater into and from the gap between both stages can be prevented, forexample, by applying a water-repellent coating 95 by Teflon (™) or thelike on the side surface of both of the stages facing each other. Bythis operation, because a non-contact state is maintained between bothstages, there is no risk of stage deformation, decrease in positioncontrol accuracy or the like, due to the contact of both stages.

In the first to third embodiments described above, the elastic sealmember is arranged, however, the elastic seal member or othersuppression members for suppressing leakage does not necessarily have tobe arranged. In such a case, both stages can be in contact directlywhile the transition is made from a state where one of the stages islocated directly under projection unit PU to a state where the otherstage is located directly under projection unit PU. Further, although itdepends on the material of both stages, the surface state and/or thesurface shape of the stages, the type of liquid and the like, in thecase the liquid does not leak due to the surface tension of the liquidduring the transition in a state where both stages are close together(e.g. the distance between the stages is 2 mm or under), thewater-repellent coating does not have to be applied. The point is thatthe transition of both stages should be made while maintaining thepositional relation, which keeps the liquid from leaking from betweenthe stages.

Further, the leakage of the water (liquid) into the gap between thestages during the transition may be permissible if the leakage is only asmall amount. Therefore, the distance between both stages during thetransition can be decided taking into consideration the permissibleamount of leakage, as well as the material of both stages, the surfacestate and/or the surface shape of the stages, the type of liquid and thelike

Further, in the first to third embodiments described above, reflectionsurfaces of the movable mirrors are not formed on the contact surfacesof the two stages. However, this is not an indispensable matter, and aslong as the leakage of the water from the gap in the two stages can beprevented, a reflection surface of the movable mirrors can be formed onthe contact surface of at least one of the stages. As such anembodiment, for example, a fourth embodiment in the description belowcan be considered.

A Fourth Embodiment

Next, a fourth embodiment of the present invention will be described,referring to FIGS. 20 to 23B. For components or assemblies that have thesame or similar arrangement as the third embodiment previouslydescribed, the same reference numerals will be used, and the descriptionthereabout will be brief, or entirely omitted. In the exposure apparatusof the fourth embodiment, only the configuration or the like of thewafer stage unit differ from the third embodiment previously described,and the configuration or the like of other parts are similar to thethird embodiment previously described. Accordingly, from the viewpointof avoiding repetition in the following description, the differenceswill mainly be described.

As is shown in FIG. 20, a wafer stage unit 150 of the fourth embodimentis equipped with a wafer stage WST′ on which a wafer can be mounted, ameasurement stage MST′ used only for measurement, and an interferometersystem including six laser interferometers (hereinafter simply referredto as ‘interferometers’) IF1 to IF6.

As is shown in FIG. 21, the point where wafer stage WST′ has a plateshaped canopy section 111 a, which is a part of the upper end section ofwafer stage WST′ on the −X side (the side facing measurement stage MST′)that projects out, and the point where reflection surfaces formed on anedge surface Se on the +X side and an edge surface Sd on the +Y side arearranged instead of the movable mirrors are different from wafer stageWST related to the third embodiment described above, however, othersections are configured in the same manner as wafer stage WST. Further,on the upper surface of wafer stage WST′ in a state where wafer W ismounted, the entire surface is to be flush (in-plane) including thesurface of wafer W and canopy or overhang section 111 a.

As is shown in FIG. 21, the point where measurement stage MST′ has aprojected section 111 c arranged on the +X side (the side facing waferstage WST′), which has a step section 111 b on the upper edge sectionthat can be engaged to the tip of canopy section 111 a via apredetermined clearance, and the point where reflection surfaces formedon an edge surface Sa on the −X side, an edge surface Sb on the +Y side,and an edge surface Sc (the edge surface of projected section 111 c onthe +X side) on the +X side are arranged instead of the movable mirrorsare different from measurement stage MST related to the third embodimentdescribed above, however, other sections are configured in the samemanner as measurement stage MST. In this case, in a state where canopysection 111 a of wafer stage WST′ and step section 111 b are engaged asis shown in FIG. 21, a completely flat surface can be formed as a whole,by the upper surface of wafer stage WST′ and the upper surface ofmeasurement stage MST′.

Wafer stage WST′ and measurement stage MST′ in the embodiment are drivenwithin a two-dimensional plane by a wafer stage drive section (80 to87), similar to wafer stage WST and measurement stage MST in the thirdembodiment previously described.

As is shown in FIG. 20, the interferometer system has three Y-axisinterferometers, IF3, IF4, and IF2 whose measurement axes are eachparallel to the Y-axis. The measurement axes respectively pass throughthe projection center (optical axis AX) of projection optical system PL,the detection center of alignment system ALG, and the position apredetermined distance away from the projection center of optical systemPL in the −X direction. The interferometer system also has two X-axisinterferometers, IF1 and IF5 whose measurement axes are each parallel tothe X-axis. These measurement axes also respectively join the detectioncenter of projection optical system PL (optical axis AX) and thedetection center of alignment system ALG. The interferometer system alsohas another X-axis interferometer, IF6 whose measurement axis is alsoparallel to the X-axis and passes the position a predetermined distanceaway from the projection center of projection optical system PL in the−Y direction.

When wafer stage WST′ is located in an area in the vicinity of theposition directly under the optical axis of projection optical system PL(a first area), and exposure of the wafer on wafer stage WST′ is to beperformed, the position of wafer stage WST′ is controlled by X-axisinterferometer IF5 and Y-axis interferometer IF3. In the descriptionbelow, the coordinate system set by the respective measurement axesX-axis interferometer IF5 and Y-axis interferometer IF3 will be referredto as the exposure coordinate system.

Further, when wafer stage WST′ is in an area in the vicinity of theposition directly under the detection center of alignment system ALG (asecond area), and detection of alignment marks formed on the wafer onwafer stage WST′ is to be performed, such as wafer alignment or thelike, the position of wafer stage WST′ is controlled by X-axisinterferometer IF5 and Y-axis interferometer IF4. In the descriptionbelow, the coordinate system set by the respective measurement axesX-axis interferometer IF5 and Y-axis interferometer IF4 will be referredto as the alignment coordinate system.

Further, when measurement stage MST′ is in an area in the vicinity of awaiting position as is shown in FIG. 20, the position of measurementstage MST′ is controlled by X-axis interferometer IF1 and Y-axisinterferometer IF2. In the description below, the coordinate system setby the respective measurement axes X-axis interferometer IF1 and Y-axisinterferometer IF2 will be referred to as the waiting coordinate system.

X interferometer IF6 measures the position of wafer stage WST′ in theX-axis direction during wafer exchange or the like, after the exposureof the wafer has been completed.

As is obvious from the description above, in the embodiment, X-axisinterferometers IF5 and IF1 are both multi-axis interferometers thathave at least three measurement axes that are separate in the Y-axisdirection and the Z-axis direction, and the output values of eachoptical axis can be measured independently. Accordingly, with theseX-axis interferometers IF5 and IF1, other than measuring the position ofwafer stage WST′ and measurement stage MST′ in the X-axis direction, therotation amount around the Y-axis (rolling amount) and the rotationamount around the Z-axis (yawing amount) can also be measured. Further,X-axis interferometer IF6 can be a multi-axis interferometer, or it canbe an interferometer with a single optical axis.

Further, Y-axis interferometers, IF3, IF4, and IF2 described above aremulti-axis interferometers, for example, that have two measurement axesthat are separate in the Z-axis direction, and the output values of eachoptical axis can be measured independently. Accordingly, with theseY-axis interferometers IF3, IF4, and IF2, other than measuring theposition of wafer stage WST′ and measurement stage MST′ in the Y-axisdirection, the rotation amount around the X-axis (pitching amount) canalso be measured.

In the description below, details on a parallel processing operationusing wafer stage WST′ and measurement stage MST′ equipped in theexposure apparatus of the fourth embodiment will be described, referringto FIGS. 20 to 23B. During the operation below, main controller 20performs the open/close operation of each valve in liquid supply unit 5and liquid recovery unit 6 of liquid supply/drainage system 32 accordingto the moving direction of the stage positioned at the first areadirectly under projection unit PU as is previously described, and thespace directly under tip lens 91 of projection optical system PL isconstantly filled with the water. However, in the description below, forthe sake of simplicity, the description related to the control of liquidsupply unit 5 and liquid recovery unit 6 will be omitted.

FIG. 20 shows a state where exposure by the step-and-scan method isperformed on wafer W on wafer stage WST′ in a manner similar to thefirst embodiment previously described. At this point, measurement stageMST′ is waiting at a predetermined waiting position where it does notbump into wafer stage WST′. In this case, main controller 20 controlsthe position of measurement stage MST′ on the waiting coordinate systemdescribed above, while controlling the position of wafer stage WST′ onthe exposure coordinate system described above.

Then, on the wafer stage WST′ side, for example, at the stage whereexposure of one lot (25 or 50 wafers in one lot) of wafer W iscompleted, main controller 20 moves measurement stage MST′ to theposition shown in FIG. 22A. In the state shown in FIG. 22A, the edgesurface of canopy section 111 a on the −X side arranged in wafer stageWST′ and the surface of step section 111 b on the −X side in measurementstage MST′ are in a state close together (or in contact), as is shown inFIG. 21.

In this case, because the width of canopy section 111 a of wafer stageWST′ in the X-axis direction is set wider than the width of step section111 b of measurement stage MST′ in the X-axis direction, this canprevent the mirror-polished edge surface (reflection surface) Sc ofmeasurement stage MST′ from coming into contact with the edge surface ofwafer stage WST′ on the −X side excluding canopy section 111 a (thesection of the edge surface on the −X side below canopy section 111 a).

Next, main controller 20 starts to simultaneously drive both wafer stageWST′ and measurement stage MST′ in the +X direction, while maintainingthe positional relation between wafer stage WST′ and measurement stageMST′ in the X-axis direction.

When main controller 20 simultaneously drives both wafer stage WST′ andmeasurement stage MST′ in the manner described above, in the state shownin FIG. 22A, the water that has been held in the space between tip lens91 of projection unit PU and wafer W sequentially moves over thefollowing areas along with the movement of wafer stage WST′ andmeasurement stage MST′ to the +X side: wafer W→wafer stageWST′→measurement stage MST′. During the movement, wafer stage WST′ andmeasurement stage MST′ maintain the positional relation shown in FIG.21. FIG. 22B shows a state where the water (the immersion area)simultaneously exists on both wafer stage WST′ and measurement stageMST′ during the movement above, that is, the state just before the wateris passed over from wafer stage WST′ to measurement stage MST′. In thisstate as well, wafer stage WST′ and measurement stage MST′ maintain thepositional relation shown in FIG. 21. In the state shown in FIG. 21, thegap between the edge of canopy section 111 a of wafer stage WST′ and theedge of the upper surface of measurement stage MST′ facing the edge ofthe canopy section is maintained at 0.3 mm or under, which makes itpossible to keep the water from entering the gap in the case the watermoves over the gap. In this case, making the upper surface of canopysection 111 a and the upper surface of measurement stage MST′ waterrepellent (contact angle to the liquid should be 80° or over) canprevent the water from entering the gap more securely. During thismovement, the interferometer beam from interferometer IF2 will not beincident on edge surface Sb of measurement stage MST′ any longer.However, substantially at the same time (immediately before or directlyafter), the interferometer beam from interferometer IF3 will start toirradiate edge surface Sb of measurement stage MST′, and at this point,main controller 20 executes the reset (or preset) of interferometer IF3.

When wafer stage WST′ and measurement stage MST′ are drivensimultaneously further in the +X direction by a predetermined distancefrom the state shown in FIG. 22B, the water will then be held in thespace between measurement stage MST′ and tip lens 91, as is shown inFIG. 23A.

Next, in parallel with driving wafer stage WST′ in the +X direction andthe −Y direction, main controller 20 drives measurement stage MST′ inthe +X direction and the +Y direction. During the drive, theinterferometer beam from interferometer IF5 will not be incident on edgesurface Se of wafer stage WST′ any longer, and the interferometer beamfrom interferometer IF6 will begin to irradiate edge surface Se.Therefore, main controller 20 presets interferometer IF6 in a statewhere both interferometer beams irradiate edge surface Se, using themeasurement values of interferometer IF5. Meanwhile, on edge surface Sbof measurement stage MST′, the interferometer beams from interferometerIF4 will be incident, therefore, main controller 20 presetsinterferometer IF4 at some point where both interferometer beamsirradiate edge surface Sb, using the measurement values ofinterferometer IF3. Further, on edge surface Sc of measurement stageMST′, the interferometer beams from interferometer IF5 will be incident;therefore, main controller 20 executes the reset (or preset, taking intoconsideration the measurement values of interferometer IF1) ofinterferometer IF5.

Then, in the manner described above, wafer stage WST′ and measurementstage MST′ are arranged as is shown in FIG. 23B where wafer stage WST′is located at a predetermined wafer exchange position and measurementstage MST′ is positioned directly under projection optical system PL. Asfor wafer stage WST′, when the interferometer beams of interferometerIF4 stops irradiating wafer stage WST′, the position of wafer stage WST′in the Y-axis direction cannot be measured by the interferometer system.However, the Y position of wafer stage WST′ can be controlled by alinear encoder or the like (not shown). Or an interferometer can beadded that can measure the position of wafer stage WST′ in the Y-axisdirection when wafer stage WST′ is at the wafer exchange position. Inthe state shown in FIG. 23B, wafer exchange is performed on the waferstage WST′ side while in parallel with the exchange, a predeterminedmeasurement is executed on the measurement stage MST′ side whennecessary. As such measurement, for example, baseline measurement ofalignment system ALG performed after the reticle has been exchange onreticle stage RST will be performed, as in the third embodimentdescribed above. In this case, the position of measurement stage MST′ inthe X-axis direction is preferably measured using interferometer IF5,instead of using interferometer IF1. By performing baseline measurementwhile measuring the position of measurement stage MST′ usinginterferometer IF5, which measures the position of wafer stage WST′ inthe X-axis direction during exposure of wafer W, alignment (positionsetting) of wafer W based on the baseline (amount) can be performed withhigh precision.

Incidentally, the reticle alignment previously described is alsoperformed with the baseline measurement of alignment system ALG, as inthe third embodiment described above.

Then, at the stage where the operations described above on both stagesWST′ and MST′ have been completed, main controller 20, for example,makes measurement stage MST′ and wafer stage WST′ return to the stateshown in FIG. 23A, drives measurement stage MST′ and wafer stage WST′within the XY plane while maintaining the state in which wafer stateWST′ and measurement stage MST′ are close together (or in contact),performs wafer alignment by alignment system ALG on wafer W that hasbeen exchanged, that is, performs detection of alignment marks byalignment system ALG on wafer W that has been exchanged, and computesthe position coordinates of a plurality of shot areas on wafer W. Duringthis wafer alignment, the position of wafer stage WST′ is controlled onthe alignment coordinate system previously described.

Then, main controller 20 simultaneously drives wafer stage WST′ andmeasurement stage MST′ in the −X direction, which is opposite to thedescription earlier, while maintaining the positional relation betweenboth stages, and after moving wafer stage WST′ (wafer W) to the positionbelow projection optical system PL, main controller 20 withdrawsmeasurement stage MST′ to a predetermined position. Also during thisoperation, the interferometer system performs preset or the like of theinterferometers in a reversed order of the description above.

Then, as in each of the embodiments described above, main controller 20performs the exposure operation by the step-and-scan method on wafer W,and sequentially transfers the reticle pattern onto the plurality ofshot areas on wafer W.

In the description above, the case has been described where baselinemeasurement is performed as the measurement operation. However, thepresent invention is not limited to this, and illuminance measurement,uneven illuminance measurement, aerial image measurement and the likecan be performed as in the third embodiment above. Further, as in thethird embodiment, various measurements can be performed when necessaryeach time a predetermined number of wafers (e.g. one) have beenexchanged, without limiting the measurement until after exposure of onelot has been completed. Further, measurement stage MST′ can have awavefront aberration measuring unit installed, and the wavefrontaberration of projection optical system PL can be measured by themeasuring operation. Or, an observation camera can be arranged onmeasurement stage MST′ so as to check the state of the immersion areaformed on the image plane side of projection optical system PL.

Further, the detection of the alignment marks of wafer W that has beenexchanged by alignment system ALG does not necessarily have to beperformed while maintaining the predetermined neighboring state of waferstage WST′ and measurement stage MST′, and the detection of thealignment marks can be started after the stages move away from eachother, or the detection of a part of the alignment marks can beperformed in a state where both stages are close together and thedetection of the remaining alignment marks can be performed in a statewhere both stages are separated.

As is described above, according to the exposure apparatus of the fourthembodiment, when a transition is performed from a first state wherewafer stage WST′ (or measurement stage MST′) positioned at a first areadirectly under projection unit PU to which the liquid (water) issupplied to a second state where measurement stage MST′ (or wafer stageWST′) is positioned at the first area, a stage drive system (configuredincluding wafer stage drive section (80 to 87)) drives wafer stage WST′and measurement stage MST′ so that canopy section 111 a on the waferstage WST′ side and step section 111 b on the measurement stage MST′side move into an engaged state, and a completely flat surface isachieved by the upper surface of wafer stage WST′ and measurement stageMST′. Therefore, it becomes possible to perform the transition from thefirst state where one of the stages is positioned at the first area tothe second state where the other stage is positioned at the first area,in a state where the water is held in the space between projectionoptical system PL and at least one of the stages (this stage switchesfrom one of the stages to the other stage with the movement) directlybelow projection optical system PL, without leaking any water from thegap between both stages. More specifically, the transition from a statewhere the water is held in the space between wafer stage WST′ andprojection optical system PL to a state where the water is held in thespace between measurement stage MST′ and projection optical system PLcan be performed during the period after the exposure operation on thewafer stage WST′ side via projection optical system PL and the water(liquid) has been completed until the measurement on the measurementstage MST′ side directly under projection optical system PL is started,without going through the process of fully recovering the water and thensupplying the water again. Further, the same applies to after themeasurement with measurement stage MST′ has been completed until theexposure by wafer stage WST′ begins.

Accordingly, it becomes possible to improve the throughput by reducing(that is, to maintain the time around the same level as a typicalexposure apparatus (a non-immersion type exposure apparatus) that doesnot perform immersion exposure) the time after the exposure operation onthe wafer stage WST′ side has been completed until the measurement onthe measurement stage MST′ side is started, and the time after themeasurement with measurement stage MST′ has been completed until theexposure by wafer stage WST′ begins. Further, because the water (liquid)constantly exists on the image plane side of projection optical systemPL, generation of water stains (water marks) previously described can beeffectively prevented.

Further, in the fourth embodiment, because canopy section 111 a isarranged in wafer stage WST′ and step section 111 b that engages withcanopy section 111 a is arranged in measurement stage MST′, even if areflection surface is arranged on edge surface Sc of measurement stageMST′ on the side where the two stages face each other, the transitionfrom a state where the water is held in the space between wafer stageWST′ and projection optical system PL to a state where the water is heldin the space between measurement stage MST′ and projection opticalsystem PL (or vice versa) can be performed without any serious problems.

Further, by performing exposure with high resolution and a larger depthof focus than in the air by the immersion exposure, the pattern ofreticle R can be transferred with good precision on the wafer, and forexample, transfer of a fine pattern that has a device rule of around 70to 100 nm can be achieved.

In the fourth embodiment above, the case has been described where canopysection 111 a is arranged on the wafer stage WST′ side and projectedsection 111 c having step section 111 b is arranged on the measurementstage MST′ side. The present invention, however, is not limited to this,and the projected section having the step section can be arranged on thewafer stage WST′ side and the canopy section can be arranged on themeasurement stage MST′ side. Further, in the fourth embodiment above,the case has been described where the edge section of measurement stageMST′ on the +X side is made of projected section 111 c, which is asingle part that has step section 111 b formed on its upper edgesection. This is because edge surface Sc on the +X side of projectedsection 111 c had to be a reflection surface, but this arrangement doesnot necessarily have to be employed. For example, if the reflectionsurface does not have to be formed, the section corresponding to 111 conly has to have a step section on the upper edge section that canengage with canopy section 111 a via predetermined clearance, and theremaining section can take any shape. Similarly, as long as canopysection 111 a is arranged on the upper edge section on the wafer stageWST′ side, the remaining section can take any shape.

Further, in the fourth embodiment above, canopy section 111 a isintegrally formed with wafer stage WST′, however, canopy section 111 acan be made from a plate member detachable from the main body of waferstage WST′.

Further, an arrangement may be employed where an elastic seal member isarranged at a position where the elastic seal member comes betweencanopy section 111 a and step section 111 b in a state where canopysection 111 a and step section 111 b are engaged. More specifically, forexample, by arranging an elastic seal member on the edge section ofcanopy section 111 a on the −X side, the water leakage between waferstage WST′ and measurement stage MST′ can be completely prevented.Further, by arranging the elastic seal member, in the case wafer stageWST′ and measurement stage MST′ come into contact with each other, theshock can be reduced. As a matter of course, the elastic seal member canbe arranged on the measurement stage side, or instead of the sealmember, a water-repellent coating can be applied to at least either thewafer stage or the measurement stage, at a position where both stagesface each other.

The concept of arranging the canopy section in one of the stages andarranging a step section in the other stage in the fourth embodimentdescribed above can be employed not only when the two stages are ameasurement stage and a wafer stage, but also when the two stages areboth wafer stages.

More specifically, for example, in the case of employing the stage unitconfiguration described in the first embodiment (refer to FIG. 2) or thesecond embodiment (refer to FIG. 12) above, because the positionalrelation of wafer stage WST1 and wafer stage WST2 in the X-axisdirection does not change, the configuration can be employed in whichcanopy section 111 a is formed in one of the wafer stages on one side inthe X-axis direction and projected section 111 c having a step section111 b made on its upper edge section is formed in the other wafer stageon the other side in the X-axis direction, as is shown in FIG. 24.

Further, for example, in the case of employing the stage unit whosepositional relation of wafer stages WST1″ and WST2″ in the X-axisdirection changes as is shown in FIG. 25A, the configuration has to beemployed where both wafer stages WST1″ and WST2″ each have a canopysection and a projected section as is shown in FIG. 25B. By employingsuch a configuration, even in the case when wafer stage WST1″ is at the−X side and wafer stage WST2″ is at the +X side or the case when waferstage WST1″ is at the +X side and wafer stage WST2″ is at the −X side,the transition from a state where the water is in contact with one ofthe wafer stages to a state where the wafer is in contact with the otherstage in a state where the water leakage is suppressed can be performed,as in the fourth embodiment previously described.

In each of the embodiments described above, when the water held undertip lens 91 is moved from above one stage to above the other stage, thewater supply and recovery can be stopped while the water is held undertip lens 91. Especially in the case when the water pressure increasesdue to the supply of water, it makes the water leak more easily from thegap of the two stages. Therefore, the water supply and recovery arepreferably stopped.

In each of the embodiments described above, pure water (water) is usedas the liquid, however, as a matter of course, the present invention isnot limited to this. As the liquid, a liquid that is chemically stable,having high transmittance to illumination light IL and safe to use, suchas a fluorine containing inert liquid may be used. As such as afluorine-containing inert liquid, for example, Fluorinert (the brandname of 3M United States) can be used. The fluorine-containing inertliquid is also excellent from the point of cooling effect. Further, asthe liquid, a liquid which has high transmittance to illumination lightIL and a refractive index as high as possible, and furthermore, a liquidwhich is stable against the projection optical system and thephotoresist coated on the surface of the wafer (for example, cederwoodoil or the like) can also be used. Further, in the case the F₂ laser isused as the light source, fombrin oil may be used as the fluorinecontaining liquid.

Further, in each of the embodiments above, the liquid that has beenrecovered may be reused. In this case, it is desirable to arrange afilter in the liquid recovery unit, in the recovery pipes, or the likefor removing impurities from the liquid that has been recovered.

In each of the embodiments above, the optical element of projectionoptical system PL closest to the image plane side is tip lens 91. Theoptical element, however, is not limited to a lens, and it can be anoptical plate (parallel plane plate) used for adjusting the opticalproperties of projection optical system PL such as aberration (such asspherical aberration, coma, or the like), or it can also simply be acover glass. The surface of the optical element of projection opticalsystem PL closest to the image plane side (tip lens 91 in theembodiments above) can be contaminated by coming into contact with theliquid (water, in the embodiments above) due to scattered particlesgenerated from the resist by the irradiation of illumination light IL oradherence of impurities in the liquid. Therefore, the optical element isto be fixed freely detachable (exchangeable) to the lowest section ofbarrel 40, and can be exchanged periodically.

In such a case, when the optical element that comes into contact withthe liquid is a lens, the cost for replacement parts is high, and thetime required for exchange becomes long, which leads to an increase inthe maintenance cost (running cost) as well as a decrease in throughput.Therefore, for example, the optical element that comes into contact withthe liquid can be a parallel plane plate, which is less costly than lens91.

Further, in each of the embodiments above, the range of the liquid(water) flow only has to be set so that it covers the entire projectionarea (the irradiation area of illumination light IL) of the patternimage of the reticle. Therefore, the size may be of any size; however,on controlling the flow speed, the flow amount and the like, it ispreferable to keep the range slightly larger than the irradiation areabut as small as possible.

Further, in each of the embodiments above, the case has been describedwhere the present invention is applied to a scanning exposure apparatusby the step-and-scan method or the like. It is a matter of course, thatthe present invention is not limited to this, and more specifically, thepresent invention can also be applied to a projection exposure apparatusby the step-and-repeat method

The usage of the exposure apparatus to which the present invention isapplied is not limited to the exposure apparatus used for manufacturingsemiconductor devices. For example, the present invention can be widelyapplied to an exposure apparatus for manufacturing liquid crystaldisplays which transfers a liquid crystal display device pattern onto asquare shaped glass plate, and to an exposure apparatus formanufacturing organic EL, thin-film magnetic heads, imaging devices(such as CCDs), micromachines, DNA chips or the like. Further, thepresent invention can also be suitably applied to an exposure apparatusthat transfers a circuit pattern onto a glass substrate or a siliconwafer not only when producing microdevices such as semiconductors, butalso when producing a reticle or a mask used in exposure apparatus suchas an optical exposure apparatus, an EUV exposure apparatus, an X-rayexposure apparatus, or an electron beam exposure apparatus.

Further, the light source of the exposure apparatus in the embodimentabove is not limited to the ArF excimer laser, and a pulsed laser lightsource such as a KrF excimer laser or an F₂ laser, or an ultrahigh-pressure mercury lamp that generates a bright line such as theg-line (wavelength 436 nm) or the i-line (wavelength 365 nm) can also beused as the light source.

Further, a harmonic wave may also be used that is obtained by amplifyinga single-wavelength laser beam in the infrared or visible range emittedby a DFB semiconductor laser or fiber laser, with a fiber amplifierdoped with, for example, erbium (or both erbium and ytteribium), and byconverting the wavelength into ultraviolet light using a nonlinearoptical crystal. Further, the projection optical system is not limitedto a reduction system, and the system may be either an equal magnifyingsystem or a magnifying system.

Device Manufacturing Method

Next, an embodiment will be described of a device manufacturing methodthat uses the exposure apparatus described in each of the embodimentsabove in the lithography step.

FIG. 26 shows the flowchart of an example when manufacturing a device (asemiconductor chip such as an IC or an LSI, a liquid crystal panel, aCCD, a thin-film magnetic head, a micromachine, and the like). As shownin FIG. 26, in step 201 (design step), function and performance designof device (circuit design of semiconductor device, for example) isperformed first, and pattern design to realize the function isperformed. Then, in step 202 (mask manufacturing step), a mask on whichthe designed circuit pattern is formed is manufactured. Meanwhile, instep 203 (wafer manufacturing step), a wafer is manufactured usingmaterials such as silicon.

Next, in step 204 (wafer processing step), the actual circuit and thelike are formed on the wafer by lithography or the like in a manner thatwill be described later, using the mask and the wafer prepared in steps201 to 203. Then, in step 205 (device assembly step), device assembly isperformed using the wafer processed in step 204. Step 205 includesprocesses such as the dicing process, the bonding process, and thepackaging process (chip encapsulation), and the like when necessary.

Finally, in step 206 (inspection step), tests on operation, durability,and the like are performed on the devices made in step 205. After thesesteps, the devices are completed and shipped out.

FIG. 27 is a flow chart showing a detailed example of step 204 describedabove. Referring to FIG. 27, in step 211 (oxidation step), the surfaceof wafer is oxidized. In step 212 (CDV step), an insulating film isformed on the wafer surface. In step 213 (electrode formation step), anelectrode is formed on the wafer by deposition. In step 214 (ionimplantation step), ions are implanted into the wafer. Each of the abovesteps 211 to 214 constitutes the pre-process in each step of waferprocessing, and the necessary processing is chosen and is executed ateach stage.

When the above-described pre-process ends in each stage of waferprocessing, post-process is executed as follows. In the post-process,first in step 215 (resist formation step), a photosensitive agent iscoated on the wafer. Then, in step 216 (exposure step), the circuitpattern of the mask is transferred onto the wafer by the lithographysystem (exposure apparatus) and the exposure method of the embodimentabove. Next, in step 217 (development step), the exposed wafer isdeveloped, and in step 218 (etching step), an exposed member of an areaother than the area where resist remains is removed by etching. Then, instep 219 (resist removing step), when etching is completed, the resistthat is no longer necessary is removed.

By repeatedly performing the pre-process and the post-process, multiplecircuit patterns are formed on the wafer.

When the device manufacturing method of the embodiment described so faris used, because a device pattern is formed on a wafer by exposing thewafer (substrate) with an energy beam (illumination light IL) using theexposure apparatus in each of the embodiments above in the exposure step(step 216), exposure with high throughput and high precision can beachieved for a long period of time. Accordingly, the productivity ofhigh integration microdevices on which fine patterns are formed can beimproved.

INDUSTRIAL APPLICABILITY

As is described above, the stage drive method of the present inventionis suitable for driving the first stage and the second stage. Further,the exposure apparatus of the present invention is suitable forsupplying liquid in the space between the projection optical system andthe substrate and exposing the substrate with the energy beam via theprojection optical system and the liquid. Further, the devicemanufacturing method of the present invention is suitable for producingmicrodevices.

1. A stage drive method in which a first stage and a second stage areindependently driven within an area in a two-dimensional plane of apredetermined range including a first area where liquid is locallysupplied and a second area located on one side of the first area in afirst axis direction, wherein during a transition from a first state inwhich one stage of the first stage and the second stage is positioned atthe first area to a second state in which the other stage is positionedat the first area, the first stage and the second stage aresimultaneously driven in a second axis direction intersecting the firstaxis direction while one of a state where the first stage and the secondstage are close together in the second axis direction and a state wherethe first stage and the second stage are in contact in the second axisdirection is maintained.
 2. The stage drive method of claim 1 whereinthe first stage and the second stage are separately driven by a set oflinear actuators that can engage freely detachably to both the firststage and the second stage and each of which can drive a specific stagein an engaged state in at least the second axis direction, the specificstage being one of the first stage and the second stage, and during thetransition, one stage of the first stage and the second stage is in anengaged state with one linear actuator of the set of linear actuatorsand the other stage is in an engaged state with an other linearactuator, and after the transition, the engagement between both stagesand the linear actuators are released respectively and then the onestage engages with the other linear actuator and the other stage engageswith the one linear actuator.
 3. The stage drive method of claim 1wherein during the transition, the liquid continues to be retained onthe stage positioned at the first area.
 4. The stage drive method ofclaim 1 wherein measurement beams are irradiated on reflection surfacesof a first mirror and a second mirror, which are respectively arrangedon the first stage and the second stage on a surface besides the surfaceon the side where both stages are close or are in contact during thetransition, and the position of the first and second stages iscontrolled based on reflection beams from the reflection surfaces of thefirst mirror and the second mirror.
 5. A stage unit comprising: a firststage and a second stage that are independently driven within an area ina two-dimensional plane of a predetermined range, which includes a firstarea where liquid is locally supplied and a second area located on oneside of the first area in a first axis direction; and a control unitthat controls the first stage and second stage so as to simultaneouslymove the first stage and the second stage in a second axis directionintersecting the first axis direction while one of a state where thefirst stage and the second stage are close together in the second axisdirection and a state where the first stage and the second stage are incontact in the second axis direction is maintained, during a transitionfrom a first state in which one stage of the first stage and the secondstage is positioned at the first area to a second state in which theother stage is positioned at the first area.
 6. An exposure apparatusthat supplies a liquid to a space between a projection optical systemand a substrate and exposes the substrate with an energy beam via theprojection optical system and the liquid, the apparatus comprising: afirst stage that is movable within an area of a predetermined rangeincluding a first area directly below the projection optical systemwhere the liquid is supplied and a second area located on one side ofthe projection optical system in a first axis direction; a second stagethat is movable within an area of a predetermined range including thefirst area and a third area located on the other side of the projectionoptical system in the first axis direction; a stage drive system thatdrives the first stage and the second stage, and simultaneously drivesthe first stage and the second stage in the first axis direction whileone of a state where the first stage and the second stage are closetogether in the first axis direction and a state where the first stageand the second stage are in contact in the first axis direction ismaintained, during a transition from a first state in which one stage ofthe first stage and the second stage is positioned in the first area toa second state in which the other stage is positioned in the first area;a first mark detection system arranged above the second area thatdetects a mark located on the first stage; and a second mark detectionsystem arranged above the third area that detects a mark located on thesecond stage.
 7. The exposure apparatus of claim 6 wherein the firststage and the second stage are both stages on which substrates can bemounted.
 8. The exposure apparatus of claim 6 wherein a part of an upperend portion in one stage of the first stage and the second stage on theside facing the other stage is a plate shaped hangover portionprotruding over an other portion, and a step portion that can engagewith at least a tip of the overhang portion via a predeterminedclearance is arranged in the other stage on at least a part of thesurface facing the one stage, and in a state where the overhang portionand the step portion are engaged, a completely flat surface of apredetermined size can be formed by at least a part of the upper surfaceof the one stage and at least a part of the upper surface of the otherstage.
 9. The exposure apparatus of claim 6 wherein the first stage andthe second stage each have a plate shaped overhang portion protrudingover an other portion in a part of an upper end portion on one side ofthe first axis direction, and a step portion that can engage with atleast a tip of the overhang portion of the other stage via apredetermined clearance on at least a part of a surface on the otherside of the first stage and the second stage in the first axisdirection, and in a state where the overhang portion of one stage andthe step portion of the other stage are engaged, a completely flatsurface of a predetermined size can be formed by at least a part of theupper surface of the one stage and at least a part of the upper surfaceof the other stage.
 10. The exposure apparatus of claim 6 wherein thestage drive system maintains the state where the first stage and thesecond stage are close together during the transition, and in at leastone of the first stage and the second stage, a suppressing member isarranged so as to suppress leakage of the liquid from a gap between thestages by being positioned in the gap between the stages during thetransition.
 11. The exposure apparatus of claim 10 wherein thesuppressing member includes at least one of a seal member and awater-repellent coating.
 12. The exposure apparatus of claim 6 whereinduring the transition, the liquid continues to be held in the spacebetween the projection optical system and the stage positioned at thefirst area.
 13. The exposure apparatus of claim 6, the apparatus furthercomprising: a first mirror and a second mirror arranged on the firststage and the second stage, respectively, on a surface besides thesurface on the side where both stages are close together or are incontact during the transition; and an interferometer that measures theposition of the first stage and the second stage by irradiatingmeasurement beams respectively on reflection surfaces of the firstmirror and the second mirror, based on reflection beams from thereflection surfaces of the first mirror and the second mirror.
 14. Adevice manufacturing method that includes a lithography step in which asubstrate is exposed with the energy beam, using the exposure apparatusaccording to claim
 6. 15. An exposure apparatus that supplies a liquidto a space between a projection optical system and a substrate andexposes the substrate via the projection optical system and the liquid,the apparatus comprising: a first stage that is movable within an areaof a predetermined range including a first area directly below theprojection optical system where the liquid is supplied and a second arealocated on one side of the first area in a first axis direction; asecond stage that is movable independent from the first stage within anarea of a predetermined range including the first area and the secondarea; and a stage drive system that drives the first stage and thesecond stage, and simultaneously drives the first stage and the secondstage in a second axis direction intersecting the first axis directionwhile one of a state where the first stage and the second stage areclose together in the second axis direction and a state where the firststage and the second stage are in contact in the second axis directionis maintained, during a transition from a first state in which one stageof the first stage and the second stage is positioned in the first areato a second state in which the other stage is positioned in the firstarea.
 16. The exposure apparatus according to claim 15 wherein the stagedrive system includes a set of linear actuators that drive the firststage and the second stage separately, which can engage freelydetachably to both the first stage and the second stage and each ofwhich can drive a specific stage in an engaged state in the second axisdirection, the specific stage being one of the first stage and thesecond stage.
 17. The exposure apparatus according to claim 16, theapparatus further comprising: a switching unit that switches a statewhere one stage of the first stage and the second stage is in an engagedstate with one linear actuator of the set of linear actuators and theother stage is in an engaged state with an other linear actuator to astate where the one stage engages with the other linear actuator and theother stage engages with the one linear actuator after the transition.18. The exposure apparatus according to claim 15 wherein the first stageand the second stage are both stages on which substrates can be mounted,and the apparatus further comprises: a mark detection system disposed inthe second area that detects a mark located on a specific stage, whichis one of the first stage and the second stage positioned directly underthe mark detection system.
 19. The exposure apparatus of claim 15wherein the first stage and the second stage each have a plate shapedoverhang portion protruding over an other portion in a part of the upperend portion on one side of a first axis direction, and on at least apart of a surface on the other side of the stages in the first axisdirection, a step portion that can engage with at least a tip of theoverhang portion of the other stage via a predetermined clearance isarranged, and in a state where the overhang portion of one stage and thestep portion of the other stage are engaged, a completely flat surfaceof a predetermined size can be formed by at least a part of the uppersurface of the one stage and at least a part of the upper surface of theother stage.
 20. The exposure apparatus of claim 15 wherein the stagedrive system maintains the state where the first stage and the secondstage are close together during the transition, and in at least one ofthe first stage and the second stage, a suppressing member is arrangedso as to suppress leakage of the liquid from a gap between the stages bybeing positioned in the gap between the stages during the transition.21. The exposure apparatus of claim 20 wherein the suppressing memberincludes at least one of a seal member and a water-repellent coating.22. The exposure apparatus of claim 15 wherein during the transition,the liquid continues to be held in the space between the projectionoptical system and the stage positioned in the first area.
 23. Theexposure apparatus of claim 15, the apparatus further comprising: afirst mirror and a second mirror arranged on the first stage and thesecond stage, respectively, on a surface besides the surface on the sidewhere both stages are close together or are in contact during thetransition; and an interferometer that irradiates measurement beams onreflection surfaces of the first mirror and the second mirror andmeasures the position of the first stage and the second stage, based onreflection beams from the reflection surfaces of the first mirror andthe second mirror.
 24. A device manufacturing method that includes alithography step in which a substrate is exposed with the energy beam,using the exposure apparatus according to claim
 15. 25. An exposureapparatus that supplies a liquid to a space between a projection opticalsystem and a substrate and exposes the substrate via the projectionoptical system and the liquid, the apparatus comprising: a first stagethat is movable within an area including a first area directly below theprojection optical system where the liquid is supplied and an areadifferent from the first area; a second stage that is movableindependent from the first stage within the area including the firstarea and the area different from the first area; a stage drive systemthat drives the first stage and the second stage, and simultaneouslydrives the first stage and the second stage in a predetermined directionwhile a state where the first stage and the second stage are closetogether in the predetermined direction is maintained, during atransition from a first state in which one stage of the first stage andthe second stage is positioned in the first area to a second state inwhich the other stage is positioned in the first area; and a suppressingmember arranged in at least one of the first stage and the second stage,so as to suppress leakage of the liquid from a gap between the stages bybeing positioned in the gap between the stages during the transition.26. The exposure apparatus of claim 25 wherein the suppressing memberincludes at least one of a seal member and a water-repellent coating.27. The exposure apparatus of claim 25 wherein during the transition,the liquid continues to be held in the space between the projectionoptical system and the stage positioned in the first area.
 28. Theexposure apparatus of claim 25, the apparatus further comprising: afirst mirror and a second mirror arranged on the first stage and thesecond stage, respectively, on a surface besides the surface on the sidewhere both stages are close together or are in contact during thetransition; and an interferometer that measures the position of thefirst stage and the second stage by irradiating measurement beamsrespectively on reflection surfaces of the first mirror and the secondmirror, based on reflection beams from the reflection surfaces of thefirst mirror and the second mirror.
 29. A device manufacturing methodthat includes a lithography step in which a substrate is exposed withthe energy beam, using the exposure apparatus according to claim 25.